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  1. Trailer Tongue Lock
  2. AMPLock
  3. Fits 2-5/16 Inch Ball
  4. Surround Lock
  5. Cast Iron
  6. Keyed Unique
AMPLock Trailer Coupler Lock for Flat Lip 2-5/16" Ball Couplers - Ductile Cast Iron

AMPLock Trailer Coupler Lock for Flat Lip 2-5/16" Ball Couplers - Ductile Cast Iron

Item # AMP44FR
Our Price: $299.00
Trailer Tongue Lock
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Use this heavy-duty cast iron coupler lock to help prevent trailer towaway theft. Fits standard 2-5/16" ball couplers with flat lips and a finger latch. Resists picking, cutting, and freezing. Tumbler offers nearly 1 million possible key codes. Great Prices for the best trailer tongue lock from AMPLock. AMPLock Trailer Coupler Lock for Flat Lip 2-5/16" Ball Couplers - Ductile Cast Iron part number AMP44FR can be ordered online at or call 1-800-940-8924 for expert service.
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  • Reviews (95)
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  • Videos (1)
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AMPLock Trailer Tongue Lock - AMP44FR

  • Fits 2-5/16 Inch Ball
  • Surround Lock
  • AMPLock
  • Cast Iron
  • Keyed Unique
  • Universal Application Lock
  • Flat Lip Style

Use this heavy-duty cast iron coupler lock to help prevent trailer towaway theft. Fits standard 2-5/16" ball couplers with flat lips and a finger latch. Resists picking, cutting, and freezing. Tumbler offers nearly 1 million possible key codes.


  • Tamper-resistant, sturdy lock deters trailer theft by preventing hookup
    • Fits over coupler, engaging it like a trailer ball does and blocking the ball opening
    • Prevents would-be thieves from hitching your trailer to their tow vehicle
  • Push-and-lock cylinder locks without the need for a key
    • Lock's location on bottom makes it difficult for thieves to access
  • Rotating-disc-tumbler lock provides maximum security
    • Nearly a million possible key codes
    • Resistant to picking and drilling
  • Heavy-duty ductile cast iron construction
    • Absorbs shock to prevent breaking
    • Resists any kind of cutting, including cutting with a torch or liquid nitrogen
  • Molded fit with swivel design decreases hold options for thieves
  • E-coat finish resists corrosion
  • 2 Keys included


  • Application: standard ball couplers for 2-5/16" balls with finger latch (as seen below)
    • Coupler must have flat lip
    • Maximum coupler width (including lip): 4-9/16"
    • Maximum lip thickness: 7/16"
  • 5-Year limited warranty

Coupler Fits:

This lock fits 2-5/16" ball couplers with a flat lip and a finger latch, as seen below.

BRHT-2516 coupler applications

Secure Locking Mechanism

This coupler lock has a disc tumbler locking mechanism. Unlike locks that use vulnerable spring-loaded pins, this ultra-secure lock is bump-proof. The cylinder has a series of rotating discs that can be correctly lined up only when you turn the corresponding key. Two identical notched keys are included to operate the lock. Because these keys feature 1 of nearly a million possible key codes, it's extremely unlikely that another individual will have a key that can open this lock.

U-BRHT-2 5/16 AMP Lock Trailer Coupler Lock 2-5/16" Ball Couplers with Straight Lip and Finger Latch - Ductile Cast Iron

Video of AMPLock Trailer Coupler Lock for Flat Lip 2-5/16" Ball Couplers - Ductile Cast Iron

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

Video Transcript for AMPLock Flat Lip Ball Couplers Trailer Coupler Lock Review

What's up, everybody, it's AJ, with Today, we're gonna be checking out this coupler lock from AMPLocks. Now this is going to work with your coupler on your trailer, and what it's gonna do, is you're gonna put the ball in the coupler, and the lock along the lip, and then it should be all locked up and nobody can mess with it, let's check it out. It's a real easy process, first you're going to put the ball up here in the coupler like you normally would. Lock that into place, and you can see it's locked in there, it's not going to go anywhere. And then we add the second part of the lock, which this part here, it's going to fit it right over the flat lip of our coupler.

And you're gonna line up this with the hole on the ball there, just slide it into place, and then lock it up. So now that ball has taken out that empty space here in the coupler, so nobody can get anything up there to wedge it out, and this is covering up the front of it too, so that's just like double protection. so people can't mess with this coupler. It's actually a pretty snug fit on our coupler today, it's moving back and forth but there isn't a lot of space and then there's not a lot of gaps, so let's test that out with a pry bar. Just going to put that into place.

Yeah, it looks like it will fit in there and you can push on it a little bit, but it's not moving anywhere. I'm not pushing that hard, but it's still staying in place pretty good. Looks like it can fit in under here on the side too, now this way, I can't really pry against anything. This way I might be able to just a little bit, but it really does take up a lot of those gaps, I mean, there's not an easy way to get this in there. So if somebody wasn't messing with it, it would take them quite a bit of time to get in there and do anything.

I think they would probably just walk on to the next trailer that doesn't have a lock on it. Another good thing to test is to see, with the latch undone, it's not going to just drop back out, it doesn't drop that ball. This is working in combination with that ball to keep this locked up nice and tight. So even if you don't have a locking pin that goes in there to keep that from moving, you still can't just get it out of that easily. Another thing to note is here at the bottom, the tumbler lock.

And I really liked that because it's going to be resistant to drilling and picking, and it's got like a million different combinations or possibilities for the key. So, chances are no one's going to have the same key and they're not going to mess with it to try and get in there. And it does come with two keys you get, and you see I just turned that and pop that button out, and that means it's disengaged. When you want to go to lock it, you just push it into place and it's locked. It's nice that when you go to set this up, you don't have to have the key in there to lock it. I like that push button 'cause you can just do that, and your keys on the side. The construction is cast iron with an E-coating so you don't have to worry about the elements bothering it at all, so if you leave it out here and it rains, or anything like that, it's not going to rust or corrode on you. The other thing is it's going to be shock absorbent, so if somebody was hit with a hammer, it wouldn't just shatter, it would absorb that shock. Taking a look at the inside of the coupler, this is going to fit trailers of coupler widths of 4-9/16" of an inch, and then a thickness lip of 7/16" of an inch. So just keep that in mind when you're looking at your trailer, this is the one that's going to fit. Overall, I really like this lock. I like that the two-in-one combo is pretty heavy duty too, I like the fact that this covers up the front of the coupler, and this is gonna take up that space on the inside. So like you saw with the pry bar, it's gonna be hard to get those angles and get in there, and like I said before, pretty sure people don't take one look at this and go, "I'm not messing with that," and going to the next trailer. Thanks for hanging out, and I hope this helps..

Customer Satisfaction Score:

Customer Reviews

AMPLock Trailer Coupler Lock for Flat Lip 2-5/16" Ball Couplers - Ductile Cast Iron - AMP44FR

Average Customer Rating:  4.8 out of 5 stars   (95 Customer Reviews)

Use this heavy-duty cast iron coupler lock to help prevent trailer towaway theft. Fits standard 2-5/16" ball couplers with flat lips and a finger latch. Resists picking, cutting, and freezing. Tumbler offers nearly 1 million possible key codes.


This is a nice lock, but there is plenty of room between the lip of the lock and the body of the trailer coupler for a prybar to be used. The coupler does have quite a bit of 'play' when installed - probably because it is a universal lock and as such it is designed to accommodate the dimensional differences between coupler manufacturers. Overall, the quality is very nice, and I have some ideas regarding how to 'tighten' up the fit between the lock and the coupler via shims. The manufacturer should consider including some shims - which could be used to provide a better fit between the lock body and the coupler.


Does its job as advertised. I leave this trailer on construction sites, and no attempted thefts yet.


This is by far the best trailer lock available on the market


Great service and product!!


Fits as described. Very solid. I feel like my trailer is definitely secure.



Good tight fit, tough construction, and a disk core. It has sat out in the elements it's whole life and the lock still spins like new. I did drop the ball portion with the key still in it and it bent the key. That's my fault though. I Like the lock.


Impressive lock. Well machined.
I was
disappointed I couldn’t engage ball with the hitch ball clamp assembly after the flange lock was installed.


Trailer still where I parked it. This lock is doing its job.


It is a little large for my 2", it fit my trailer with a 2 1/2" coupler, I wouldn't get another one.


Kate was extremely professional and knowledgeable about the trailer coupler lock that I needed. She was very efficient and helpful in placing the order and when the lock arrived it fits perfectly. It is on my trailer right now and is exactly what I needed thanks to Kate and her performance. Give her a big monetary raise and recognition before her peers.


This is the best trailer tung lock I have ever used. Heavy duty, well built, with a very unique key system that was well thought out. YES, I would highly recommend the AMP LOCK SYSTEM FOR YOUR TRAILER. YOU WONT BE DISAPPOINTED.


Heavy duty and very well made. No one's going to get it off!


I have a car hauler with 2 inch receiver rolled lip. This coupler lock has what I wanted. It should prevent the opportunitistic thief from taking trailer.its a solid lock . I leave a trailer off-site so it's just added insurance. It will take some grinding to get off. Key is heavy and solid so shouldn't break in lock. Happy with purchase.


I am impressed with the quality of the lock. The day we put it on in Buffalo, our sons bikes were stolen out of his garage. We were parked right in front of it. We were happy to have had it on.


AMPLock coupler lock is fantastic. Used daily. Very well made, strong and def trust regularly to keep my trailer safe.


Nice trailer lock, its expensive but if some one steals the boat it would be very in expensive then. :)


Easy to use. Heavy duty. Seems very sec ure.


Fit and finish are perfect Fits the Demco no lip 25K


The lock is heavy duty and great. But it DID NOT work on my 2022 Jayco Micro. The lock mechanism needs to be about ?” shorter to clear the lower lip of the trailer hitch. e trailer wanted a 20% restocking fee plus for me to pay for shipping since I was outside my return window. The trailer was in for service so I could not test it out before the return policy ended. So I am either going to sell it or try to modify it myself.I would not buy it again for my 2022 Jayco.


This lock is a solid and hefty piece of equipment. Make sure to get the right model for your set-up. The width of the lip on my trailer was 3.75” and the lock fits like a glove.


This AMP Lock Trailer Coupler Lock might be expensive but you get what you pay for here I believe. I have purchased 3 of these based on what I believe to be a quality product.

by: 03/07/2024

great lock


I had a friend recommend this to me a year ago. Excellent lock for securing my car hauler! I recommend this to anyone that needs a trailer lock.


Nice lock for my Air Stream Bambi, just what I needed, between this lock and my new wheel chuck locks from it should not get stolen again. thanks Etrailer for my new lock setup.!

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See what our Experts say about this AMPLock Trailer Tongue Lock

  • How to Tell if AMPLock Trailer Coupler Lock Will Fit Trailer Coupler
    Great question! The AMPLock Trailer Coupler Lock # AMP44FR works for couplers that connect to a 2-5/16" hitch ball and the coupler has a flat lip design. This is pretty standard for trailer couplers but I'm also linking a review video of this coupler lock for you to check out. If you take note at the start of the video you'll see the flat lip design I was talking about. If you have the flat lip coupler but you use a 2" hitch ball to tow then you can use the part # AMP64FR instead. This...
    view full answer...

Info for this part was:

Employee Andrew K
Installed by:
Andrew K
Employee Lindsey S
Written by:
Lindsey S
Employee Dustin K
Video Edited:
Dustin K
Employee Aidan B
Video by:
Aidan B

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