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Master Lock 2-5/16" Trailer Coupler Lock
(68 reviews)
Price: $60.20
In Stock
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- All Info
- Reviews (68)
- Q & A (0)
- Videos (2)
- Photos
Master Lock Trailer Tongue Lock - 378DAT
- Fits 2-5/16 Inch Ball
- Keyed Unique
- Surround Lock
- Master Lock
- Universal Application Lock
Trailer coupler lock guards against trailer towaway theft.
Features:
- Fits 2-5/16" (48 mm) ball diameter couplers of the following brands:
- Atwood
- Will not fit Flat Nose style couplers
- Reese
- Fulton
- Shelby
- Valley
- Dutton-Lainson
- Putnam
- Acme
- Ideal
- Atwood
- Advanced locking mechanism resists picking and prying
- Silver powder coated anodized aluminum construction is rust and corrosion resistant
- Easy to install and remove
- Lifetime guarantee
378DAT Master Lock 2-5/16" Trailer Coupler Lock
Video of Master Lock 2-5/16" Trailer Coupler Lock
Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.
Video Transcript for Master Lock 2-5/16" Trailer Coupler Lock Review
Today we're going to be taking a look at the Master Lock 2 5/16 Inch Trailer Coupler Lock, Part Number 378DAT. This trailer coupler lock guards against trailer tow-away theft. So now we're out here at our trailer and we'll go ahead and show you how to install this. We have the key at the end of the lock and the locking mechanism is pretty unique. It's going to help prevent anyone from actually getting in there and picking it. Now we have our trailer coupler here.
Simply we're just going to insert the ball into the coupler. So we have . The ball is inside the coupler and now with the key actually in it in the lock position, we can push it forward and there's actually this kind of locking tab mechanism that is inside of here that . It's going to allow you to push it forward but won't allow you to push it backwards. We'll push it all the way forward and we can put it in the locking position and remove the key. You can see when someone tries to take it off, this big steel block here will rest on your coupler's lip and it's going to prevent anyone from taking it off.
To remove it, simply just need to insert our key in and turn it to the unlocked position. What that does is we can just simply pull out that big steel bar and release it from the coupler and we're ready to hook up and drive away. Now that we've gone over how to install and remove the Master Lock 2 5/16 Inch Trailer Coupler Lock, that'll complete today's review of Part Number 378DAT. .
Ratings & Reviews
4.7
68 reviews
by:
Doug A.
10/19/2012
materials and finish. I like the idea that it allows my other padlock to still be used - two locks will slow down the thieves. My trailer sits out under a canopy and is exposed where the public can see it. This lock gives me much greater security.
by:
Pat T.
08/12/2015
Bought this as an added piece of security. Fits the 2-5/16 coupler really good.
by:
Dean
04/22/2026
Great product, exactly what I needed, perfect fit
by:
Kirt
04/28/2026
It doesn’t fit. I’d like to return it
by:
Richie
06/11/2017
Great locking device, I feel comfortable leaving my trailer in my drive with this lock attached, Its also a good idea to disconnect the battery inside trailer so the electric tongue jack can't operate for those who have that, last thing you want is to worry if your trailer will be there when you get back home
by:
John M.
02/12/2013
This is my third coupler lock. It is a replacement for one that was cut off. a relative borrowed my trailer, and stored it for the winter. In mid winter the storage place closed for good and he had to bring me back my trailer he couldn't get the lock open because it was frozen. It had rained and the temp dropped. So he decided to cut it off. I can tell you he worked hard and long to cut it and the Masterlock that was also locking the coupler. locks keep honest people honest. when he locked it in the fall if he would have wrapped the lock with plastic wrap he could have used the key and saved himself time and the cost of my locks........
by:
Derek T.
05/13/2013
Lock works perfectly on a 2-5/16" trailer coupler (28' trailer). I previously tried the less expensive "universal" lock from the local retail store, but it didn't work because the cheaper yellow lock has a U shaped bar the goes over the coupler. Larger couplers are wider and the "universal" lock. This coupler lock locks from the side (no bar over the top). It fit by coupler perfectly snug. Appears to be robust as well. I would definitely recommend this lock to people that need to lock larger sized trailer couplers.
by:
Richard
04/27/2016
Locks work great, they fit all of our various trailers and having both the 2" and the 2-5/16" locks the same key is awesome!
Thank you so much!
Richard
Thank you so much!
Richard
by:
Richard
04/27/2016
Locks work great, they fit all of our various trailers and having both the 2" and the 2-5/16" locks the same key is awesome!
Thank you so much!
Richard
Thank you so much!
Richard
by:
Arlan R
07/12/2017
Not really fair to rate poor, since the product does not work on our trailer. Perhaps you could provide information the lock does not work on rolled lip trailer tongues used on Airstream trailers. I realize you say, works on most 2 5/16 trailers. So now we get to return the lock. If the lock would retract completly, it would clear the lip.
by:
Michael
04/10/2014
I was so happy that hitch lock works on my trailer I tried others and they did not work I had a master lock for a 2 inch but they said that would work on a 2 5/16 ball but it did not thank you so much Michael
by:
Victoria A.
06/05/2014
Works great, Love the fact that I feel much safer having it on my trailer.
by:
Steve D
08/22/2016
Product works great. Easy to install we have several trailers got the locks all keyed the same couldn't be happier
by:
Bob
02/01/2011
trailer! The width of the flange area surrrounding the hitch-ball-socket on the trailer tongue is 4.5 inches. I tried other locks from West Marine and Lowes and they were too small/narrow. This lock resolved the problem and works great!
by:
Alaska SE
09/08/2016
Received this lock along with a trailer hitch lock. Works on my trailer. Arrived as expected and would order again.
by:
Steve V
05/27/2014
Product came just as advertised. They even upgraded my shipping at
no charge. Just after I ordered I had to call to make a change, Customer service was very helpful. I buy a lot of the internet,
It would be a pleasure to do business with these people again.
Thanks
Steve
no charge. Just after I ordered I had to call to make a change, Customer service was very helpful. I buy a lot of the internet,
It would be a pleasure to do business with these people again.
Thanks
Steve
by:
Larry B
07/01/2014
This product worked great on my bike trailer. I had a hard time finding something that was compatable with the surge brake set up.Top notch.
by:
Steven
05/15/2018
great product as usual. I have always had good service and good product from etrailer... Thanks
by:
John P
07/13/2015
The Masterlock trailer coupler lock worked as advertised. I'm very pleased. Anyone wanting to make my trailer their's will think twice.
by:
Jeff
12/28/2022
One of the best locks I have found. Super fast shipping. Great price. etrailer gets 6 stars
by:
Mike A.
01/09/2017
Both products are exactly what I was looking for. The quality of the jack and trailer jack are great. Angela from etrailer was very friendly and helpful to deal with. The delivery time from time of order was quick.
by:
Sam M
08/21/2017
The best hitch lock I have ever purchased. Love it.
by:
William S
04/21/2015
Fits as described. Lock is smooth. Etrailer service was great.
Hope this lock is never really tested.
Hope this lock is never really tested.
by:
J M
07/16/2012
is very easy to pull the key assembly out of its housing and lose locking mechanism pieces. This lock certainly kept my boat from leaving my driveway. By anyone. Including me. (It also takes about 5 minutes with a cutting wheel to remove, so make sure you're never out of ear-shot of this thing.)
by:
DAVID L.
08/15/2011
IT FIT GREAT. WAS DELIVERED IN A TIMELY MANNER. IT WAS PACKAGED VERY WELL FOR SHIPMENT. CUSTOMER SERVICE AND FOLLOW- UP WAS GREAT. PRODUCT WAS REASONABLY PRICED.'
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See what our Experts say about this Master Lock Trailer Tongue Lock
Info for this part was:
Expert Research:
Mike L
Expert Research:
Robert G
Expert Research:
Michael H
Expert Research:
Jameson C
Expert Research:
Victoria B
Installed by:
Jeff D
Installed by:
Matthew K
Video by:
Alan C
Video Edited:
Chad S
Updated by:
Wilson B
Updated by:
Michael B
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Victoria A.
6/5/2015
Working great and would buy from you when the time comes that I need something for my trailer.