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Adapter 4 Pole to 7 Pole and 4 Pole w/Test Lamps

Item # C57674

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Curt 7 Blade,4 Flat Wiring - C57674
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Curt 7 Blade,4 Flat Wiring - C57674
Curt Wiring Adapters - C57674
Wiring C57674 - 4 Flat - Curt
C57674 - 4 Flat Curt Wiring Adapters
Curt Plug and Lead Wiring - C57674
Curt Multi-Function Adapter Wiring - C57674
Curt 4 Flat Wiring - C57674
C57674 - Plug and Lead Curt Wiring
Wiring C57674 - Plug and Lead - Curt
Curt Wiring Adapters - C57674

In Use/Installed

C57674 - Plug and Lead Curt Wiring Adapters on 2011 Subaru Outback Wagon
Curt Wiring - C57674 on 2011 Subaru Outback Wagon
C57674 - Plug and Lead Curt Wiring on 2011 Subaru Outback Wagon
Curt Wiring Adapters - C57674 on 2011 Subaru Outback Wagon
Curt Wiring - C57674 on 2011 Subaru Outback Wagon
Curt 7 Blade,4 Flat Wiring - C57674 on 2011 Subaru Outback Wagon

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  • Wiring Adapters
  • Multi-Function Adapter
  • 4 Flat
  • 7 Blade
  • 4 Flat
  • Plug and Lead
  • Curt
This multi-function, vehicle-end connector converts any 4-way flat, vehicle-end plug to a combination 7-way outlet and 4-pole flat outlet. Lowest Prices for the best wiring from Curt. Adapter 4 Pole to 7 Pole and 4 Pole w/Test Lamps part number C57674 can be ordered online at etrailer.com or call 800-298-8924 for expert service.


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  • Reviews (198)
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Curt Wiring - C57674

This multi-function, vehicle-end connector converts any 4-way flat, vehicle-end plug to a combination 7-way outlet and 4-pole flat outlet.


Features:

  • Adapts 4-way flat to both 7-way round and 4-way flat
  • Includes integrated test lamps which display proper connections
    • Shows if you wiring on the trailer isn't working properly - burned out bulbs, poor connection, etc.
  • Includes mounting bracket and hardware
    • Distance between vehicle mounting holes center to center: 2-1/4"


57674 Curt Adapter 4 Pole to 7 Pole and 4 Pole w/Test Lamps



C57674 Installation InstructionsInstallation Details C57674 Installation instructions


Video of Adapter 4 Pole to 7 Pole and 4 Pole w/Test Lamps


Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.




Video Transcript for Curt Wiring C57674 Review

Today we're going to be reviewing part number C57674. This is the Curt Wiring Adapter from a 4 way flat to both a 7 way round and a 4 way flat. The multi function vehicle end connectors are going to convert any 4 way flat end connector vehicle plug to a combination of a 7 way outlet, and that's also going to have the 4 pole flat outlet as well. It's going to include the integrated test lamp. You can see that it's going to have the display right here which is going to display the proper connections. This is going to indicate and show if the wiring on your trailer isn't working properly.

It's going to show whether you have burned out bulbs, poor connections, things that go along with that. It's also going to include your mounting bracket and all the hardware that you need to get the socket mounted to the bracket. It's going to come with four screws and it's going to come with the washers and the nuts that you need to get the bracket . or the socket mounted to the four connections there on the mounting bracket. To go over the functions of the wires real quick. You can see here that it's going to expose a 4 way flat connector.

This is designed to plug into your existing 4 way, and then it's going to have four more wires that are exposed. All the wires are going to have butt connectors on them. The white wire's going to have a ring terminal on it for easy connection, so those are already in place, they're already installed and ready to be connected. Your white wire is going to be your ground wire. This is to be grounded to the vehicle frame. The yellow wire is going to be the center pole of the 7 way connector.

It's normally used for connection to the reverse light circuit. Your blue wire is for the connection of the electric brake feed from the brake controller. Then your black wire is going to be the twelve volt wire and will need to be ran to the positive terminal of the vehicle battery. It needs to be ran through a forty amp circuit breaker. That is going to be sold separately.

You can find that right here on our website with part number PK54540. This wire will be used to maintain the charge of a trailer mounted accessory battery and/or breakaway battery. Those already have the easy connectors on them that way all you have to do is make a few connections, get some wiring. If you need the full setup for installing a brake controller, all the additional wiring, you can use part number ETBC7. That's a kit that we here at Etrailer put together to make it easier for you. You can find that right here on our website. I want to focus here on the 7 way connector. It's got a spring loaded lid so when it's not in use it's going to remain closed that way it's going to protect the connection points on the inside. It's got the indicators here on this side. Each light has a code right next to it. The first one's going to be twelve volt. That's going to be for the twelve volt hot lead. If that's connected correctly and working properly that will light up. BK is the output from the brake controller so if you do not have a brake controller installed this light will not light up. The back up, BU, is for the reverse lights. If this circuit is not connected on the vehicle it will also not light up. RT stands for right turn. TM stands for the running lights or tail and marker lights, and then LT stands for left turn. The overall dimensions of the actual socket here is going to be . the housing that goes around the socket, that's going to give us a measurement of three and three eighths by three inches. Once you have it ready to be mounted with the bracket all you have to do is run your wires through here. It's going to fit around that socket portion back here really nicely. It's going to go right through the appropriate holes. It's going to make sure that all the mounting holes line up, and then you're going to take your 4 way flat, it's got a couple grooves on it that slide into the bracket face. Once you have those on you just push it in. It's going to hold it right there for easy connection. You're going to have your 7 way round connector right here, and then right next to it you're going to have easy access to the 4 way flat. That's going to do it for our review of part number C57674. This is the Curt Wiring Adapter converting from just your 4 way flat to both a 7 way round and a 4 way flat system. .


Customer Reviews

Adapter 4 Pole to 7 Pole and 4 Pole w/Test Lamps - C57674

Average Customer Rating:  4.8 out of 5 stars   (198 Customer Reviews)

This multi-function, vehicle-end connector converts any 4-way flat, vehicle-end plug to a combination 7-way outlet and 4-pole flat outlet.

- C57674

by:


Working perfectly after one year. Easy to install. Thanks for such a great product! 570896



- C57674

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I use both 4 pole flat and 7 pole connections on our trailers so this fit the bill. Here, I welded a bracket to use it on our Dodge Journey. 563114



- C57674

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Nicely made. The indicator lights on it are super useful. 569166



- C57674

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crimp connectors should be the heat shrink type 569841



- C57674

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I recently had a receiver hitch installed on my 89 Silverado and the wiring was merely zip tied to the safety chain connection. Well that didn't sit well with me. I wanted a more permanent wiring connection point. So I purchased your 4 flat to 4 flat and 7 way plug and installed it. So far so good. The installation turned out perfect and it looks good. The test lights are a great thing as well. I couldn't be happier. 420882


Comments

Perfect. The only issue I had was the 4 flat didn’t stay in the bracket but that was easily remedied with a couple of holes and some safety wire. Other than that I’d say u have one of the best setups you could ask for.

Lawrence L - 08/16/2018

42419

- C57674

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I need the ability to pull trailers with both 4 Pole and 7 Pole connections and this adapter did the trick. It's heavy duty and I think the extra few bucks for the Test Lamps was well worth it. 64739



- C57674

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Last project built. Used etrailer for almost all parts, including the 7 pin wiring harness. Friend wants one now so started another one. I will be getting all the parts from etrailer... 486395



- C57674

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This is the second vehicle I have installed this adapter on. We tow a Coleman popup and another smaller trailer so we need both the 4-pin and 7-pin adapters. The test lamps are great to confirm that you have installed the wiring correctly. 401368



- C57674

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Great customer service on-time delivery super fast shipping product was just as described works well and just what I was looking for. 452971



- C57674

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Looks good, easy to install. 555328



- C57674

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The 4 Pole to 7 Pole adapter works great, and the indicator lights signal you that every pole is receiving power when connected to the trailer. This will be great for diagnosing a burned out bulb. I utilized a piece of sheet aluminum to mount the adapter to the underside of my Volvo XC70 bumper cover, and it is working great as installed. Was a great buy and a good value. 542151



- C57674

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I installed this 4 to 7pin adapter with the T-one harness 118449 and the Drawtite hitch on my 2016 Toyota Highlander. I think the install was 1st rate. This adapter allows me to connect either a 4 pin or 7 pin plug. Nice. Very simple to check out the installation with the test lights. Adapter looks rugged and well made. The 4 pin receptacle that slides into the bracket should have better retention though. Also I provided a picture of the 4 wire cable from the car harness to the adapter as it exits the storage compartment. I removed the grommet/seal. Made an X cut in the center. Forced the cable through it. Made a waterproof seal with RTV. 322171



- C57674

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Product worked fine 554613



- C57674

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The bracket was too wide for the OEM hitch and cover on a 2013 Highlander (see photo). I had to grind down part of the the bracket so it would clear the plastic cover. The top two mounting screws did not line up. I had to elongate one of the holes. The 4 pin connector merely slides into the side of the bracket, rather than fitting in like a grommet, so I'll bet it comes out one day. The wiring on the back of the 4 pin connector is visible when looking at the side of the bracket, making for a less than clean look. 82915



- C57674

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Easy to hook up and performs as designe d. 550261



- C57674

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I really liked the idea of having the LEDs to let me know if I was having any problems with the wiring harness, but I did find a problem with it. I installed the wiring harness myself, using the instructions on the website, but after connecting everything I realized that the LED for 12v power is always on. It is not switched by the key, so although an LED should have low draw, this might not be a good idea on a work truck that stays parked for long stretches. 80885


Comments

I am still very happy with this adaptor, but I did put back in the plug on my brake controller so I could unplug it when the trailer was not connected, the brake light was on, and I disconnected the continuous 12v. Also, make sure your 4 wire connector is clean or you might have dim lights. Although the LEDs are useful, I found a plug in tester to be more accurate because of the false brake signal I was getting.

Chris H - 05/19/2014

4322

- C57674

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2013 Dodge Durango Looks great. Nice and clean installation. 134266



- C57674

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Works great 550038



- C57674

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Great product I used this to convert my 4-way harness to a 7-way + 4-way harness on my 2011 Toyota Sienna. Everything went really well. The only very small complaint I had about this product is the length of the white ground wire. It was too short to reach a good grounding point on the frame so I had to go buy some extra wire and connectors to extend it. Make that cable about 3 ft longer, and just provide the ring terminal and this would be a perfect product. Installing it makes me want to splurge on a tow controller and charge line... 135750


Comments

HiI have a toyota sienna 2011 and i want to tow a pop-up camper. Mine has a towing package. The camper is around 2400 lb. in your case do you think a brake controller is necesary?can you tell me What kind of cable do u buy to extend the white ground cable?Di d u buy the no drill tie bracket?

-- comment by: Aldo - 06/27/2014

5189
Comments

Aldo. We towed a popup trailer that was little less than that loaded weight without any issue. This was a one time rental for us. We towed up over Vail Pass in Colorado without any issue at all. The engine and transmission on the Sienna could tow a lot more weight, it is limited due to the suspensiontire rating.The only problem we faced is that when hitched we couldnt open the rear door of the sienna due to the trailer jack on the tongue of the trailer.If I was to tow regularly I would invest in a break controller, charge line, and a Weight Distributing Hitch. The main limitation in towing with a sienna is the hitch weight.No I didnt buy the tie bracket. The hitch I purchased 75696 had a built in bracket that this fit on perfectly just had to get a few screws/nuts for it.I just bought some 12 guauge auto wire at autozone.

-- comment by: Daniel S - 06/30/2014

5220

- C57674

by:


Great product! Sturdy and weather-proof connections and wires! Easily installed. Thanks Curt and etrailer.com for an awesome item! 68991



- C57674

by:


Works great so far. 539853



- C57674

by:


Got the part faster than expected. Although no directions, install video on their web site made putting on my truck easy to figure out. Just wish it came with a couple of self tapping screws for the mounting bracket. Nice product, it was perfect solution for me, so I don’t have to get the expensive factory 7-way/ 4-way adaptor. 512234



- C57674

by:


Purchased this along with part#Hm42115. Super easy install, everything works great. 2000 Dodge Ram 1500 without the 7-way plug. Called customer service before I started and they told me exactly what I needed and got it ordered 509996



- C57674

by:


excellent product ,easy to install 516505



- C57674

by:


Fast shipping, great products that are as shown. Excellent product reviews and how to videos. a great shopping experience! 382311


Comments

Product works flawlessly. Has held up well to harsh weather and salt of Pa.

Dale C - 05/19/2018

38671
Comments

Perfect

Dale C - 05/19/2018

38700

- C57674

by:


good price, simple install, and works.. 513005



- C57674

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Used as an external connector with the converter kit. Looks and works great. 581375



- C57674

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The test lights are a nice touch and it looks sleek all mounted up. Definitely worth the extra. 579087



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easy to install 499204



- C57674

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This is a good harness. Easy to install, convenient, and still going strong after a year. 496960



- C57674

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What's good completely satisfied.. 495254



- C57674

by:


Absolutly amazing product easy installation and never gave me a slight problem. etrailer.com has a vast amount of information available for any questions or call there are numerous customer service reps and for me as of today my fabrication company will be using them for all our trailer parts because of the knowledge they give save me alot of time and headaches . Also there prices are unbeatable. Thank You 493297



- C57674

by:


Working great so far 492232



- C57674

by:


Highly recommend, this is my second one for my other truck! 488387



- C57674

by:


It was nice to find the plug and pigtail combo to make the job go much faster Thanks 478330



- C57674

by:


I bought this for a 2013 F-150 with the Tow package. I had to install the OEM brake controller and the class 4 hitch as well as the 4 to 7 adapter . The etrailer videos convinced me that I (shade tree mechanic) could do this. I was going to give this a 4 star rating because no instructions came with the package and the color of the wires did not match the YouTube example. I had no idea what wire was which:) then the review popped up in my email and the PDF with instructions was attached. This went in easy peasy . In hindsight I could have just looked it up rather then complain about the lack of attached instructions. I feel like such a millennial. 476205



- C57674

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Very easy to install with great instruc tions 474344



- C57674

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Went together hassle free 470515



- C57674

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great fit , works awesome 465553



- C57674

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Works great 463883



- C57674

by:


etrailer has become my go to supplier for trailer parts and vehicle accessories. Great prices, accurate product descriptions and easy to navigate site! All products purchased have been of excellent quality and delivered promptly...well done! If you only want to do a job one time, quality pays .... 463827



- C57674

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Product was delivered in new condition on date advertised. I have not used it yet but it looks exactly like what it is supposed to look like. 452070



- C57674

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Fit perfectly 443929



- C57674

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Product is top quality and arrived very quickly in excellent condition. 5 stars ! 443444



- C57674

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Good quality product, delivered on time easy to install. 442674



- C57674

by:


Exactly what I needed to convert my 2017 Expedition four pin to a seven so I can pull my camper. Great price and really fast delivery. Thanks etrailer. . 440295



- C57674

by:


Installed and have camped for one season using this 7-pin connector. Works great. I did make one mistake, I didn't add a relay to break the aux power connection when my vehicle is not running so the aux power LED is always lit. Got a number of comments about that this season. Might have to add a relay... 434040



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Works as it should,easily installed 433471



- C57674

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Works well 433464



- C57674

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I have all ready replaced it , because it did not work the way that it should. 430203


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Ask the Experts about this Curt Wiring
Do you have a question about this Wiring?


  • How to Install a 7-Way Trailer Connector to Add a 12 Volt Power Lead to a Trailer
  • It sounds like you are missing a wire for the running lights on your trailer. Trailers that are wired for lights will have 4 or 5 wires, one for right stop/turn, one for left stop/turn, one for ground and one, possibly two, for running lights. Does your trailer have functioning turn signals, brake lights and running lights? If the two brown wires you mentioned are separate wires from the green and brown and yellow and brown wires, then you have a wishbone harness, which means you have a...
    view full answer...

  • Wiring Diagram for the Curt 4 Pole to 7 Pole Adapter # C57674 And Wiring for Trailer Brakes
  • The wiring for the Adapter 4 Pole to 7 Pole and 4 Pole, item # C57674, is wired as follows. The white wire is grounded to the vehicle frame as you have indicated. The Yellow wire is the center pole of the 7-Way connector and is normally used for connection to the reverse light circuit. In your case you will not need the yellow wire. The blue wire is for connection of the electric brake feed wire from a brake controller. You will need a brake controller in your Sienna to activate the...
    view full answer...

  • Installing a 7-Way Trailer Connector on a 2017 Subaru Outback Wagon
  • That is correct for your 2017 Subaru Outback we only carry 4-way trailer connectors that are a direct fit. However, once you install the 4-way it can be converted to a 7-way, if that's what your trailer needs. Of the 4-way connectors for your Outback I recommend the Tekonsha # 118467 because we always have great success with them. To install the harness you'll need to locate the factory connector in the Subaru's rear cargo area. Then install the included fuse. I've linked an install...
    view full answer...

  • What do the Codes for the Test Lamps Mean on CURT Adapter 4 Pole to 7 Pole and 4 Pole # C57674
  • On the CURT Adapter 4 Pole to 7 Pole and 4 Pole w/Test Lamps, # C57674, the test light codes are as follows: 12V = 12 volt hot lead BK = output from brake controller (if no brake controller is installed, this light will not light up) BU = reverse lights (if this circuit is not connected on the vehicle it will not light up) RT = Right Turn TM = running lights (tail/marker lights) LT = left turn
    view full answer...

  • Adding a 7-Way and Brake Controller to a 2015 Ford Expedition with Factory 4-Way
  • From what we have found the 2015 Ford Expedition that came with a factory 4-Way connector will need a little bit of hardwiring to install a brake controller and 7-Way connector. You will need # 37185, some wire (more on that later), a brake controller, and a brake controller wiring harness. The 37185 will plug into the 4-Way. Then you will ground the white wire to the frame. That will leave a blue wire, black wire, and purple wire. The purple wire is for reverse lights so if the trailer...
    view full answer...

  • Adding 7-Way Trailer Connector to 2014 Toyota Tacoma without Factory Tow Package
  • It sounds like your 2014 Toyota Tacoma did not come with a factory tow package. What can happen sometimes is that on models that did not come with the factory tow package not all of the wiring or contacts will be present. You would either need to by all of the tow package parts or you would need to return the harness and install an aftermarket one designed for models without the factory tow package. If you want to add a 7-Way to the truck you would start by installing a 4-Way using #...
    view full answer...

  • How to Wire Up a Curt Brake Controller on a 2011 Chevy Silverado
  • For a color to color application you will run the black wire from the brake controller to the red/black wire from your truck, the white wire from the controller to the white wire of your truck, the red wire from the controller to the light blue/white wire from your truck, the blue wire from your controller to the dark blue controller of your truck. I attached a picture of a chart to make this easier also. I also attached a video of a brake controller being installed on a similar 2011...
    view full answer...

  • Trailer Brake Controller Installation on a 2014 Toyota Tacoma Pre Runner Without Tow Package
  • I checked your recent order and I see the components you already have: Curt 4-Pole to 7-Pole Adapter # C57674 and Tow Ready T-One Vehicle Wiring Harness # 118496. Since you have an under-dash brake control port you can use a plug-and-play harness to connect a brake controller such as the Prodigy P2, part # 90885, which is one of the most popular and reliable proportional brake controllers we offer. First I suggest you test the under-dash port to ensure it is active. The presence of wiring...
    view full answer...

  • Do I Need To Install A Brake Controller To Activate Or Deactivate Surge Trailer Brakes In Reverse?
  • Great question. Let me cover brake activation first. If you wish to have active braking on a hydraulic system when backing up, you would need to have Electric over Hydraulic brakes and not a surge brake coupler. Surge brake couplers do not allow active braking when in reverse. To add the electric over hydraulic system, it will require a brake controller like # 39523 and an electric over hydraulic brake actuator like the HydraStar Vented Marine Electric Over Hydraulic Actuator for Disc...
    view full answer...

  • Equipment Needed to Install 7-way Trailer Connector on RV and 1996 Toyota 4Runner
  • The Curt # C57674 you mentioned would be a fine choice. For the RV, you'd plug in the C57674 adapter to the existing 4 pole, which would provide lighting for the trailer. If the trailer doesn't have brakes, your install would be complete. If the trailer has brakes, you'd need to install a brake controller using a # 5506 brake controller install kit. The kit includes 25 feet of wire, which wouldn't be enough for an RV. Extra wire is sold by the foot as part # 10-2-1. For the 4 runner,...
    view full answer...


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Info for this part was:

Test Fit:
Joe V
Photos by:
Theodore B
Expert Research:
Michael L
Video Edited:
Zack K
Expert Research:
Robert G
Expert Research:
Michael H
Expert Research:
Jeff D
Expert Research:
Jameson C
Video Edited:
Joshua S
Test Fit:
Nicholas E
Video Edited:
Jacob T
Expert Research:
John H
Updated by:
Adele M
Expert Research:
Adam R
Expert Research:
Rachael H
Expert Research:
Jeffrey L
Video by:
Alan C
Video Edited:
Chris R
Updated by:
Sarah W
Video by:
Zach D
Photos by:
Stacy F
Test Fit:
Andrew S
Test Fit:
Brent H

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