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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
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Our Price: $10.43
Trailer Coupler Locks
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Master Lock Trailer Coupler Locks - 605DAT
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Lowest Prices for the best trailer coupler locks 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 (114)
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  • Videos (2)
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Master Lock Trailer Coupler Locks - 605DAT

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

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 Syler Coupler Lock Review

Today we're going to take a look at the MasterLock, Trailer style Coupler Lock, part number 605DAT. As you can see, it's a really nice, small, compact design which will make it extremely difficult to cut off or tamper with. The body of the lock is surrounded by brass with a case hardened interior, along with a case hardened pin. The pin itself is 1/4 inch in diameter, and the width from the inside of the pin hole is 3/4 of an inch. Now, our lock will come with the lock and body itself, along with 2 keys. Key will unlock the pin. As you can see, when you pull it back, I'm going to go ahead and take the key out of the way, then we've got the hardened pin that will go into the hardened body that fits right down over the pre-drilled hole in the trailer coupler, not allowing it to be unlocked. It will help to prevent trailer theft. To take it off we simply take on of our 2 keys, line it up with the tumbler, unlocks the pin, and we can remove it.

We're ready to head on down the road. That will do it for the look at our MasterLock Trailer Coupler Lock, part number 605DAT, on our trailer. .

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   (114 Customer Reviews)


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.


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.


Lock seemed cool but I never used it because it didn't fit my trailer.

This lock is designed to fit couplers ranging from 1.875 inches to 2 inches.
-- Etrailer Expert Thomas M - 12/20/2021


So far, so good! I got what I payed for!

so far so good...
Wayne - 04/21/2022


Fine,works well


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.


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:),


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.

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.
-- Etrailer Expert Mike L - 03/29/2019


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

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.
-- Etrailer Expert Heather A - 11/11/2017


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.

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.
-- Etrailer Expert Mike L - 02/27/2019


Great products at a reasonable price


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.


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


Unfortunately this didn’t fit my trailer coupler. Which I didn’t notice until after I had ordered it, my fault. I gave it to my father in law and he loves it.


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


Excellent lock. The hasp on the receiver covers 95% of the bolt so there is nothing to cut. Feels well made and heavy for its size. Good theft deterrent.


Great product and great service.


Great service


Well built, sturdy, works perfectly with my trailer.


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

After 2 years the lock is still working as expected. No issues at all !!
Scott R - 05/17/2018


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


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.


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.


This same lock was on my father-n-laws bout when he past away and we had to get metal grinder to get it off. This is a very safe lock to put on any trailer.

Show More Reviews

Ask the Experts about this Master Lock Trailer Coupler Locks

  • 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...
    view full answer...
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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.
    view full answer...
  • 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.
    view full answer...
  • 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.
    view full answer...
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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.
    view full answer...
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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...
    view full answer...
  • 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...
    view full answer...
  • 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.
    view full answer...
  • 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...
    view full answer...
  • 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.
    view full answer...
  • 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...
    view full answer...
  • Recommended Lock for Demco Hijacker UMS Double Pivot 5th Wheel Hitch for Ford Super Duty Prep Pucks
    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...
    view full answer...
  • 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...
    view full answer...
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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
    view full answer...
  • 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 # DT25013KA and for the coupler latch lock, use # 605DAT. ..
    view full answer...

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Info for this part was:

Employee Mike L
Expert Research:
Mike L
Employee John H
Expert Research:
John H
Employee Wilson B
Updated by:
Wilson B
Employee Hannah L
Updated by:
Hannah L

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