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  1. Trailer Coupler Locks
  2. Master Lock
  3. Fits 1-7/8 Inch Ball
  4. Fits 2 Inch Ball
  5. Fits 2-5/16 Inch Ball
  6. Surround Lock
Master Lock Trailer Coupler Lock - 1-7/8", 2" and 2-5/16" Ball Couplers

Master Lock Trailer Coupler Lock - 1-7/8", 2" and 2-5/16" Ball Couplers

Our Price: $28.65
You Save: 38%
Trailer Coupler Locks
Shipping Weight: 1.73 lbs
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Keep your trailer safe from towaway theft with this universal coupler lock. Its tough frame fits in and around most 1-7/8", 2", and 2-5/16" ball couplers; and it has a bright red color and heavy-duty construction to deter theft. Great Prices for the best trailer coupler locks from Master Lock. Master Lock Trailer Coupler Lock - 1-7/8", 2" and 2-5/16" Ball Couplers part number ML389DAT can be ordered online at or call 1-800-940-8924 for expert service.
  • All Info
  • Reviews (807)
  • Q & A (0)
  • Photos

Master Lock Trailer Coupler Locks

  • Fits 1-7/8 Inch Ball
  • Fits 2 Inch Ball
  • Fits 2-5/16 Inch Ball
  • Surround Lock
  • Keyed Unique
  • Master Lock
  • Universal Application Lock

Keep your trailer safe from towaway theft with this universal coupler lock. Its tough frame fits in and around most 1-7/8", 2", and 2-5/16" ball couplers; and it has a bright red color and heavy-duty construction to deter theft.


  • Heavy-duty coupler lock deters trailer theft by preventing hookup
  • Large size and heavy weight defend against attempts to break or shatter lock
  • Wafer-tumbler lock mechanism resists picking and prying
  • 1-Piece housing slides to fit tightly around your coupler
  • Powder coat resists rust and corrosion
    • Red color provides a visible theft deterrent
  • 2 Keys included


  • Application: most 1-7/8", 2" and 2-5/16" couplers
    • Fits standard lip, rolled lip, straight lip, surge brake, hammer blow, and UFP couplers
  • Limited lifetime warranty

Note: This product cannot be keyed alike.

Instructions for Locking the Trailer Coupler

  1. Insert key and turn clockwise to unlock.
  2. Pull the ball out from the lock body as far as it will go.
  3. Insert the ball of the lock into your coupler's ball socket.
  4. Push the lock body in so that it surrounds your coupler.
  5. Turn key counterclockwise to lock.

389DAT Master Lock Universal Trailer Coupler Lock - 1-7/8", 2" and 2-5/16"

Item # ML389DAT

Customer Satisfaction Score:

Customer Reviews

Master Lock Trailer Coupler Lock - 1-7/8", 2" and 2-5/16" Ball Couplers - ML389DAT

Average Customer Rating:  4.8 out of 5 stars   (807 Customer Reviews)

Keep your trailer safe from towaway theft with this universal coupler lock. Its tough frame fits in and around most 1-7/8", 2", and 2-5/16" ball couplers; and it has a bright red color and heavy-duty construction to deter theft.


Great locks!! I feel a lot better leaving all three of my trailers at home with these locks on my trailers! Definitely recommend!


I have multiple trailers with different ball hitch sizes and Master Lock fits all of them well.


It's a great product. It looks good on the trailer, and you can see it from very afar. And there is no way to saw it off, break it apart, or something like that. The construction is basically rounded, and there is nowhere you can find a starting point to place a saw or breakaway device on it. I have also bought different lock from Reese, and it looks wimpy, and easy to take it apart, or saw it off as some reviews have suggested. It's also easy to put it on and take it off. Just love the product. Here I attach some pictures in the campgrounds, etc.


Glad to see they went back to the original design. I have a chrome colored one I bought 13 years ago that is this style, still working. About 10 years ago I bought a 2nd one for my other trailer, and it was nothing like this one - cheap plastic everywhere, could easily be defeated. Backed into it once, and all the plastic broke off revealing just how flimsy it was. Was pleasantly surprised to see Master Lock went back to this much better design. I expect to get over 10 years out of this one.



Working great! No issues whatsoever. I keep the moving parts, including the key tumbler well lubed with white lithium grease, so this one is going to last.


This is my second order from and the experience was rough due to the postal service on my first order but the staff was amazing at helping me work to find the shipment and even called my local post office. I was sold on this company and now my church uses them for all our trailer needs. They are extremely good at communications and updated me every step of the way including who worked with my package and even contacting me to ask if I wanted an alternative part that would have been here sooner. I love working with this company!


Recently bought a boat and the trailer did not have any way to lock the tongue that I could see. After seeing that my stepson had a trailer with this style lock on it and seeing that it would be virtually impossible to pry it off I did some research. I have purchased from etrailer in the past and trust them to only sell the best. I ordered it and received it in a timely manner. It fits perfectly and I now feel my trailer and boat are secure. Who would doubt the Master Lock brand anyway!?!



Still working great, no complaints here.


Got this coupler lock for my boat trailer, easy to put on and take off.
So far it is working as expected, as do all the products I have purchased so far from etrailer.


Doesn't fit on a 2 5/16 equipment trailer. Made for small, lawn-mower trailers.

Etrailer Expert

Sierra K.


I am sorry this coupler lock did not work for you. I think the hump on top of your coupler is the culprit. I think item # C48CR would fit better.


Part looks great right out of the package... I have a 2 5/16" Ball coupler and the lock works perfectly on it... I'm thinking the lock is not coming off of the trailer without the key... Couldn't be happier with the lock...


Must be working... my trailer hasnt been stolen. I use every time in storage and at campgrounds. Easy to use.. Adjusts to fit snugly to coupler.. Doesnt bind up when installing or removing.. design much easier to use than some others.


Universals lock, great for many applica tions


I received the Master Lock Trailer Coupler Lock that I ordered. It was delivered in just a few days just a it was supposed to. It is exactly what I was looking for. It will help detour anyone from stealing my trailer ! I am extremely happy with the lock and etrailer ! I think this is a great company with great pricing on there products ! I will recommend them to everybody and will be ordering with them again real soon ! It was an easy and excellent experience. Great customer service too ! Thanks etrailer !


I feel much better about parking my trailer on the street with this lock on the hitch. Not only does it lock up the hitch securely but the bright red color signals to prospective thieves that this trailer cannot be towed.
It is easy to attach and easy to remove. Also very compact so it can be stored easily. The shipping time was less than I expected. is my goto supplier for my trailer accessories.


So far the product looks, feels and works great. Shipping was very fast.


This is a terrific design since unlike padlocks, can't easily be cut with bolt cutters. I like the bright red color which tells a thief there is a lock to deal with from a distance. I think someone who wants your trailer can probably defeat any system you use, so the goal is to make it tough as possible and I think this lock does that.


Universal lock


Appears as though each of the coupler locks will perform well. Both fit the 2” and the 2 5/16” couplers sufficiently to protect the trailers from thieves.


I need to return it . It doesn't fit on my trailer.

Etrailer Expert

Jenny N.


I will have our Customer Service team contact you about returning the lock. In the meantime, I want to find a lock that will work for you. Can you tell me how it is not fitting? What type of coupler do you have?


Simple design, reliable and common master lock key. 1 squirt of oil once per year keeps it excellent while living outside in daily coastal marine layer (salty dew) passes my needs test


I installed this trailer lock as soon as I purchased it. All I have done is spray the lock with WD40 a couple times and the lock has protected my favorite boat with NO problems at all.


This is just the anti-theft deterrent device we have been looking for. We have an Excavation business and keep a lot of expensive tools and equipment in a 6x12 trailer. We can sleep at night knowing our trailer will still be there in the morning. This thing is very easy to put on and take off.


Nice lock. It’s nice that there is nothing to really cut on it. Latches on nice and strong. Easy to use. You could even use a default latch lock with it. Hope it holds up as good as it looks. Will review again after awhile.


Nice tool, I like that it will adjust easily for different depths so it will fit more than one size trailer tongue. It pulls in snug and with a couple firm smacks with a 2 pound hammer is still works just fine.


Easy to find the correct size, price point is great. My go to site for auto accessories.


More security for my trailer while looking good.

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