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  1. Trailer Tongue Lock
  2. Master Lock
  3. Keyed Unique
  4. Latch Lock
  5. 3/4 Inch Span
  6. Brass
Master Lock Trigger Style Coupler Lock for 1-7/8" and 2" Couplers

Master Lock Trigger Style Coupler Lock for 1-7/8" and 2" Couplers

Item # 605DAT
Our Price: $13.99
Trailer Tongue Lock
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Great Prices for the best trailer tongue lock from Master Lock. Master Lock Trigger Style Coupler Lock for 1-7/8" and 2" Couplers part number 605DAT can be ordered online at or call 1-800-940-8924 for expert service.
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  • Reviews (139)
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  • Videos (2)
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  • Used (1)

Master Lock Trailer Tongue Lock - 605DAT

  • Keyed Unique
  • Latch Lock
  • 3/4 Inch Span
  • Master Lock
  • Brass
  • Universal Application Lock

Master Lock Trigger Lock for 1-7/8" and 2" Couplers

  • 1/4" Shackle diameter
  • 11/16" Shackle length
  • Protected case-hardened steel shackle resists cutting and sawing
  • Built-in anti-sawing pin for maximum protection
  • Solid brass case for corrosion resistance
  • Precision pin tumbler mechanism for superior pick resistance


605DAT Master Lock Trigger Style Coupler Lock for 1-7/8" and 2" Couplers

Video of Master Lock Trigger Style Coupler Lock for 1-7/8" and 2" Couplers

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

Video Transcript for Master Lock Trigger Style Coupler Lock Review

Hello neighbors. It's Brad here at etrailer. And today we're taking a look at the Master Lock Trailer Coupler lock four inch and seven eighths and two inch couplers. Now, most of the time trailers kind of sit idle, unless they're constantly attached to a vehicle, or if they are at a campsite like this RV. But unfortunately, a lot of times they will sit in storage or sit idle in a parking lot somewhere. And honestly, they're pretty easy to take for someone to just back up, hook up, and there goes your RV.

Well, this is a nice way to deter that. This simply just locks through where we unlock our coupler and the fact that we can't open this up, makes it to where this is not easily attached to just any vehicle. Now, not only is it gonna be great when you have your trailer stored, but also when you're attached to your vehicle and you have the ball in the coupler, you can also latch it on there. And that way, if you're stopping for gas or staying night somewhere else and you're not having your vehicle attended to, it's gonna stay locked on the ball. No one's gonna be able to detach that and take your trailer.

You can see this perfectly fits here with our three quarter inch span on our two inch coupler. And this also works with inch and seven eighths. So this is obviously designed for this. There's not a whole lot of wiggle room here and it goes in perfectly with this nice little spring loaded pin. Now those tight clearances are gonna make it nearly impossible for anyone to cut the pin because the hard and steel is actually resistant to cutting and sawing.

Obviously to go through this is gonna be extremely tricky but also this is an anti-sawing pin design for that maximum protection. So the fact that you can't get in here to saw this out, means that this is going to stay on until you open it up with the keys. Now, part of your RV or trailer sitting idle means that it's probably out in the element. So snow, rain, whatever weather comes around, it's going to wear and tear on pretty much every component of the trailer. Now this is made of solid brass here, so that's gonna be resisting corrosion.

So that's gonna be good to hold up long term. And also the tumbler on the lock, this has a superior pin made for preventing any type of picking. And in fact, the keys are uniquely keyed. So even if someone has some master key locks, or keys for their locks, you don't have to worry about them having the same one. The only one that's gonna open it up is the keys that come with it. So as we open this up, our pin's gonna just simply slide out here and we're ready to go. Overall, I think this is a very inexpensive investment to become a deterrent. That way you are protecting your investment. So I'd like to think that this is gonna be cheap insurance to prevent your RV or trailer from disappearing. Now, if you do have a two and five 16ths coupler, the three quarter inch span is just not really wide enough to allow to go on the latch here. But Master Lock does have an option available that has a 7/8 span that's gonna be perfectly fit and still keep that nice tight spot to where no one can saw through it. But you are gonna wanna pick up that 7/8 span. And that was a look at the Master Lock Trailer Coupler Lock four inch and seven eighth and two inch couplers..

Customer Satisfaction Score:

Customer Reviews

Master Lock Trigger Style Coupler Lock for 1-7/8" and 2" Couplers - 605DAT

Average Customer Rating:  4.7 out of 5 stars   (139 Customer Reviews)


This is a nice lock that is secure from bolt cutters; Just a little more security.


Great quality piece. Problem was it would not fit my trailer.


Smooth and reliable addition to anti-theft protection.


Well built, sturdy, works perfectly with my trailer.


I purchased the Master trigger lock as a secondary backup to a trailer coupler lock. I will be using both to protect my pontoon boat and trailer. I purchased the master lock because of the master lock name.


This lock is still performing flawlessly. Great product !! etrailer is a great vendor to by accessories from. Great products and customer service !!

Scott R.


After 2 years the lock is still working as expected. No issues at all !!


Unfortunately there wasn't enough information on this product on the website for me to determine ahead of time that the pin in this lock was too large to fit through the hole in my trailer coupler. I assumed it was standard and it is not. Now it is out of the package and I cannot return it and I cannot use it. Was a waste of money.

Etrailer Expert

Mike L.


As mentioned on the product description page, the locks shackle pin is 1/4 inch in diameter. A photo showing all the lock dimensions is also shown.


It was very stiff and the key didn't work well when it was new. After a year of use and being left in the Florida rain to do it's job, it still works. The key works better now but the lock still has stiffness to it and is difficult to manipulate. There is a spot of brown rust at the key hole which is strange for a lock that is made of brass and has internals that should be brass or impervious to oxidation. Still after a year outside in Florida I am impressed that it works so well.

Etrailer Expert

Mike L.


Try using powdered graphite in the lock opening. Graphite is one of the best solutions Ive found for a dry lubricant for locks that wont attract dirt and grime like a spray lubricant would.


Simple, effective and affordable boat trailer lock that I use at boat landings and on my boat trailer when it’s stored in my driveway. I like the fact that the main body of the lock is brass so it doesn't rust and the chromed shackle is protected by the trailer latch so it's not vulnerable to bolt cutters.


The lock, in terms of a device, appears to be well designed and produced. The problem, from the perspective of a purchaser, is the amount of conflicting and somewhat irrelevant technical information provided by Master Lock about the product. Documentation focuses on the application, specifically the corresponding trailer hitch ball size (1 7/8" and 2" couplers). Unfortunately, this same documentation then outlines physical dimensions of the lock itself stating a 1" wide opening in the lock and 7/8" depth from the center of the pin to the lowest extent of the lock opening - designed to extend over the coupler trigger mechanism. I researched additional technical documents for part number 605DAT locks, including that of the manufacturer, and found references to applicable couplers as large as 2 5/16" - again referring to the same physical dimensions of the lock opening (width 1" depth 7/8"). After discussions with etrailer customer support (Thanks Lisa D.) who then talked directly with Master Lock (who seemed oddly unable to validate the physical dimensions of the lock), and given the lock is only $10, I decided to buy the lock from etrailer . The lock arrived, and unfortunately, the lock's opening is not 1", it is 3/4". The point here is that Master Lock should review their technical documentation and provide accurate dimensions of the lock opening which will allow potential customers to make corresponding measurements of their coupler trigger mechanisms to inform their purchase decisions independent of coupler ball size. As a final note, it appears that Master Lock does not manufacture a trigger lock device with a 1" wide opening to fit 1" wide coupler triggers. I am considering modifying the lock which I purchased in an attempt to achieve a 1" wide opening by machining the widest section of the lock body. It appears that there might be enough pin depth to accomplish this. Yes, this will compromise the strength of the lock, but this device is only going to deter "honest" thieves in any case:),


Looks to be solidly made.Does not look to be easy to break off


The lock is advertised as fitting a 1 5/8 and 2” coupler. That’s why I ordered one. The package is clearly marked as fitting a 3/4” coupler. Does not fit my trailer. Not impressed

Etrailer Expert

Heather A.


Karen,Thank you for your review. The length of the shackle pin is 3/4. If the trigger on your coupler is wider than 3/4 this will not work.


I have been buying trailering parts from E trailer for a few years and have never been disappointed, great name brand products at a great price, shipping is fast, and order is always complete... 2" trailer ball with a 1 1/4" shank for a class 5 hitch is impossible to find at local retailers... Thanks to E Trailer, no clunky receiver adaptors, just the right ball mount for the receiver, and the right ball for the ball mount.. Thank you very much...


Placed order on line early evening, Patrick called me half an hour later to let me know that the tires were out of stock. He told me the tire would be available in a few weeks, or he pointed out an alternative tire.
Since I wasn't in a rush I told him I'd wait till they were in. Received them a little sooner then expected, well packed in a box.
Most companies would have just placed the order on back-order, some not telling you. Tires look good on well galvanized rims.
Would definitely do business with etrailer again.
Thank, John


This is a great product. I am on my 5th or 6th lock of this exact design. Not because it is of bad quality but because I have had a lot of trailers. When ever I sold a trailer I always gave the new owner the lock. I had one sit for 3 or 4 years on an unused trailer. Put in the key and it unlocked with out a problem A little WD40 and it was as good as new.


Excellent response Good people to deal with


This product didn't actually work for me because it did not fit the coupler on my trailer. The build quality is excellent but since I can't use it I can't comment on the durability of the lock.

If you choose to go with this lock, take some time to measure the coupler on your trailer and look at the inside dimensions of this lock (they are shown in a photo in the description - 1") to ensure that you can use this before you buy. I can use this on a utility trailer so I'll keep it. Otherwise, typical Master Lock quality.


Works exactly like it should. Quality b uilt.


What can I say, it's a Master lock. It fits snugly on the latch of my trailer coupler, allowing me to secure it in the open or closed position as needed. After a year in the Florida sun and rain, it still looks and operates the same as when I purchased it.


It is in the heat and the sun and the weather 24/7. The locking pin corroded a bit and the brass exterior is a bit tarnished, but the lock works just fine. Glad I bought it.


Excellent coupler lock!!! Pin pops out easily and re-locks with ease. made of solid brass and a steel pin. A good deterrent.


Bought this lock for my utility trailer. Shipping was on time and product is exactly what I wanted. Happy buyer


Simple and easy to use. I sprayed a little lube into the mechanism to keep it moving and resist moisture. Design works well to ensure the lock sits well on the coupler. Much better than a simple pad lock.


Looks and feels like a good quality lock with a positive latch in the locked position. Replaces another, cheaper coupler lock, feel better about having this one on the trailer.


Received this lock along with a trailer hitch lock. Works on my trailer. Arrived as expected and would order again.

Show More Reviews

See what our Experts say about this Master Lock Trailer Tongue Lock

  • Should Adding a Padlock to a Yoke Style Coupler Keep the Coupler from Coming Off of the Tow Vehicle
    I only had one photo of yours come through so it is a little hard to tell but you should be able to add your padlock style coupler lock, like the Master Lock # 605DAT, to keep your coupler from opening. Attached is a review video of the discontinued Atwood Yoke style coupler AT80072 where you can see that the padlock would attach to. I'm guessing you've already tried attaching the lock and you are still able to open up the coupler with the trailer coupled to your tow vehicle? If that is...
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  • Recommended Trailer Coupler and Trigger Lock
    If the Fastway Universal Coupler Lock for 1-7/8", 2" and 2-5/16" Couplers - Key 312, # FA86-0015-312, coupler is not snug, it may not be installed correctly. I've attached a video review for you to check out and make sure. If it is installed correctly and still doesn't meet your needs, then I recommend a different style of coupler lock like the Master Lock Trailer Coupler Lock - 1-7/8", 2" and 2-5/16" Ball Couplers, # ML389DAT. You may also be interested in a trigger lock like the Master...
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  • Availability of Keyed-Alike Coupler Locks
    There are coupler locks that can be keyed-alike, but the Master Lock Trigger Style Coupler Lock # 605DAT that you referenced cannot. Check out the Trailer Coupler Lock # e98884. You can order these keyed-alike if you select that feature before you hit add to cart. I attached a link to all the keyed-alike coupler locks we offer also.
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  • Recommended Keyed Alike Lock for Latch Style Trailer Coupler
    We sure can, but the Master Lock # 605DAT lock you'd looked at isn't available keyed alike. We do have options for keyed alike coupler locks, however. I'd recommend a latch lock such as the etrailer brand # e98890 for a 7/8 inch span or # e98885 for a 1/2 inch span. The locks are constructed of stainless steel for superior corrosion resistance and are available keyed alike. Just choose 'keyed alike' on the drop down menu on the product page and choose your desired quantity. You'll want...
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  • Coupler Lock for Trigger Latch Coupler that has 3/4 inch Span
    We have the MasterLock Trigger Style Coupler Lock part # 605DAT which has a span of 3/4 inches like you said you need that would work well. You are correct and the tighter the latch opening is to the trigger latch of the coupler the harder it would be for a thief to get in there and cut the shackle.
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  • Lock Recommendation to Fit Trigger Latch of Fulton Coupler
    For the Fulton Fast-Lok Coupler # F346000301 you referenced you would want the Master Lock Trigger Style Coupler Lock # 605DAT. Check out the picture I attached that shows it locking tightly to the trigger of a coupler. The pin diameter is 1/4 inch and is 11/16 inches long.
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  • Replacement Key For a Single Post MasterLock Padlock
    We do have the Replacement Key # MLK1 for MasterLock locks. You will need to know the number for the key that fits your lock when placing your order. The Master Lock Trigger Style Coupler Lock # 605DAT is our closest style MasterLock to the single post you have.
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  • Can an Order for Multiple Tow Ready Locks Be Keyed the Same
    Many of the lock products we offer can be ordered in multiples that are keyed alike and some of the Tow Ready brand locks are among these. The link at right will take you to our main page for locks that can be keyed alike, such as our coupler lock # e98888. You can use the filters on the linked page to select the type of locks you need - gooseneck, lunette ring, standard coupler, etc. Once you select the product you want you can select the Keyed Alike option from the drop-down menu above...
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  • Coupler Lock for Fulton Fas-Lok Trailer Coupler for 2 Inch Balls
    The pin hole is 1/4 inch which is a standard size for most trailer couplers. You can use lock # 605DAT which is designed for 1-7/8 and 2 inch couplers. I have included a link to a video review of this lock for you.
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  • Can I Get Additional Keys With The Master Lock Trigger Style Coupler Lock # 605DAT?
    While we are not able to provide matching keys with the Master Lock Trigger Style Coupler Lock # 605DAT it uses the common Master Lock key blank. If your local hardware store does not have this key once you have the key code you can order replacement Keys # MLK1 in whatever quantity you like.
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    The Demco Hijacker UMS Double Pivot 5th Wheel Hitch - Single Jaw - Ford Super Duty Prep Package - 21K # DM8550033 secures to the pucks of your Ford with turning handles that are "locked" in place by pins that are 3-3/4 inches long and 3/8 inch diameter. We have had customers that choose to increase the security of their hitch by using a padlock like the Master Lock Stainless Steel Padlock with Shielded Shackle - 3/8" Diameter Shackle # ML40D or Master Lock Trigger Style Coupler Lock for...
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  • Locking Hitch Pin, Coupler Lock and Coupler Latch Lock for 3 Inch Receiver
    The span of the hitch locks included with the Reese Tow and Store lock kit don't have a span long enough to work with a 3 inch receiver. However, you could piece together a kit that'd work for you. For the receiver lock, I'd recommend the Draw-Tite # BD580412 which offers a 4 inch span and uses a high security key. For the coupler lock, use # FA86-0015-318 and for the coupler latch lock, use # 605DAT. ..
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  • Can the Master Lock Trigger Style Coupler Lock for 1-7/8" and 2" Couplers Be Keyed Alike
    I have a solution for you, but the Master Lock # 605DAT is not available as a keyed alike lock. However, you can get the etrailer Trailer Coupler Latch Lock - 7/8" Span - 1/4" Diameter - Stainless Steel # e98890 keyed alike and it will offer the same function to lock your coupler latch. This lock is made from durable stainless steel and comes with a dust cap for the lock face to keep it free from moisture and debris. I've linked a review video of this lock for you to check out, but these...
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  • Recommended Trailer Coupler Lock For 5 Wide Coupler
    The surround-type trailer coupler locks can only fit couplers that have a maximum width of 4-1/2". For a 5" wide coupler you will need to use a latch lock such as the Master Lock Trigger Style Coupler Lock for 1-7/8" and 2" Couplers # 605DAT or Trailer Coupler Lock # e98886
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  • Is the Masterlock Trigger Style Coupler Lock Available Keyed Alike
    The Master Lock Trigger Style Coupler Lock # 605DAT is only available as keyed unique. For a keyed alike option you can look at the etrailer Trailer Coupler Latch Lock # e98889.
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  • Shackle Diameter of BOLT Covered Padlock
    The shackle diameter of the Bolt lock part # BLT59FR is 5/16 inch. The # 605DAT has a 1/4 inch diameter though.
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  • Replacing Lost Key To Bulldog Hitch Lock
    I have a solution for you, but we do not carry replacement keys for the Bulldog Trigger Style Coupler Lock # BD580404 . The way you would determine the correct replacement key would be with what is usually a 3 digit number engraved or marked on the side of the lock; these models usually had a CCP on one side and LB### marked on the other which would give you the key number. If you can't find a replacement key, I recommend replacing this with a Master Lock Trigger Style Coupler Lock # 605DAT...
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Do you have a question about this Trailer Tongue Lock?

Used Items Available
Used Picture for Master Lock Trigger Style Coupler Lock for 1-7/8" and 2" Couplers

Condition: Like New

Notes: May have damaged packaging or minor cosmetic blemishes.

Our Price: $11.95
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Info for this part was:

Employee Mike L
Expert Research:
Mike L
Employee John H
Expert Research:
John H
Employee Jacob T
Video Edited:
Jacob T
Employee Dustin K
Video by:
Dustin K
Employee Wilson B
Updated by:
Wilson B
Employee Hannah L
Updated by:
Hannah L
Employee Bradley B
Installed by:
Bradley B

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