Master Lock 378DAT Trailer Coupler Lock, 2-5/16-Inch

Very happy with this product. This is a more modern version of some of the other ones that I was looking at. I tried the style that slides on like a gorilla style lock that has a little pin that pops up. Those wiggle and you can get them off. This design is simple yet , I feel very effective. Super easy install. It definitely is a better way. Highly recommend. Note : I have a 2 5/16 ball. This model is designed for the 2 5/16 ball. 378 Model. Fits perfect.

Have tried other types of locks on my trailer that were either hard to install or left the ball socket exposed which makes it vulnerable to someone being able to modify a ball to fit around the normal latch. This lock covers the hole completely and the plunger contacts above the flange of the tongue so the lock can't be easily removed.

I like the exact ball fit on this lock instead of a universal hitch lock because I also lock the hitch closed on the lock for added security. Universal hitch locks have a smaller ball that will fall out of a larger connector if someone is successful at breaking the lock. Any lock can be broken by a determined thief, but hopefully this will be enough of a Deterrent, or make enough noise to attract attention.

As you may notice in the photo, I have a Reese brand hitch lock that did not fit and I returned to Amazon with 0 problems. The new lock is really durable, functional, and easy to install. I tried every way I could to defeat the lock. I was not successful. This is a recommend from me. In time with more removal and installs, I anticipate the rating changing to a 5.

This RV or simply for use as a trailer lock is easy to use and was purchased for my piece of mind whether our trailer is at home or while on a trip. I bought the unit to fit the 2 5/16 standard RV trailer hitch. Of course if someone really wants to steal something, they will, but this is a very stout lock and ball attachment that I feel would take quite a bit of effort to damage enough to get it off the hitch. It is easy to install and remove, with the key of course! It's not awkward to me but some could find the unit heavy for them to use. I bought a used unit from Amazon, it saved money and was just as new when I got it. I doubled it too by getting the hitch lock pin lock so it will take more time and effort in getting 2 and not just 1 lock off the hitch if anyone decides they want my trailer more than I do!

I have written VERY few reviews, but this one NEEDED to be written. The second time I was robbed was when some scum stole our 20-foot enclosed trailer, worth about $10,000. The trailer belonged to our business but was being used to hold personal belonging while our new house was being worked on. Total value of stolen items is about $20,000. One of our business neighbors was able to find security video of the trailer being stolen but there was not enough detail to ID the vehicle used or the thieves. The first time I was robbed was when Master Lock sold this piece of crap as a “lock”. It’s funny that their motto is “a brand you can trust.” Unfortunately, I did trust that brand. Master Lock should be sued for selling this as a lock, it does not even make a good paper weight. The specifications on Amazon say this thing weighs 3.6 pounds, 3.6 pounds! Maybe a package of 4 weigh 3.6 pounds! This thing is made from pot metal, and weighs less than 1 pound… Anyway, what the video that our neighbor had showed was that the scum that stole the trailer took less time breaking this “lock” off the trailer than it takes to install it! Well, Master Lock does say that it is “easy to install and remove”. The thieves wrapped a cable around the coupler “lock” and an expensive Master Lock pad lock (used to lock the coupler latch) and their truck, moved the truck forward (no lurching, just moved it forward) and both locks just popped off. Now, look at the photos of the coupler “lock” this thing fell a part right at the ball, look at the material it’s made from, cheap cast metal with a void in it. While you’re at it, the photos show corrosion, Master Lock claims that it “resists rust and corrosion” and while the trailer was parked on the San Francisco bay, it was only 5 months old and nothing else, including bare metal that the plumbers down the block have outside, rusted. I originally purchased this lock because we had one for years, but that one is made from solid (real) steel, not this pot metal junk. Stupid me, I didn’t notice the difference when this lock arrived. I will not buy anything Master Lock again, including American Lock which is owned by Master Lock. Thanks to a previous review by someone else (which I can no longer find), who’s recommendations I confirmed with a lot of my own research, I have replaced the crappy Master Lock “locks” with the following items; while these are expensive, the quality is obvious, and they cost a LOT less than the insurance deductible: AMPLOCK U-BRP2516 RV/Trailer Coupler Lock, 2 5/16 coupler (real steel - weighs 12lbs!!) - $265 AMPLOCK U-HLP58 Hitch Lock (for receiver tube 2'' X 2'') - $99 Abloy PL330 Brass Padlock for the coupler latch and chains - $82 When parked I will either take the wheels off (all 4 of them) or, for over night parking (when in use), I will wrap a KRYPTONITE cable (the thickest one that will fit in the wheels) through the holes in the wheels and lock them with either the Abloy PL330 or the ABUS 92/80 ($69). The theory with all the locks is to slow them down, then if they are really determined – GPS trackers for trailers and all expensive equipment. I’m going with “Find it Now” brand, for our motorcycles, trucks, trailers and equipment [due to compact size for the motorcycles]. If we did not have the motorcycles to protect [we’re a motorcycle business] I would go with “One Step GPS”. Master Lock “…provides peace of mind from a brand you can trust.” Not anymore!

I like the item but it does not fit the 40-foot gooseneck trailer I have. The gooseneck receiver is beefy to the point, this item does not open wide enough to pass over the bottom edge of this gooseneck.

Does what its supposed to do

medium quality - does the trick however the metal doesn't seem as strong as I would want for the price. so far it's doing the job but not my favourite

Work Great!

De qualité mais dispendieux!

After 15 years of use I bought my second one.. love it, great trailer lock

Great peace of mind.