Cover image for the trailer lock buyer's guide

The Best Trailer Lock (Hitch & Coupler) to Prevent Theft

After four days of research into 20+ trailer locks for both hitches and couplers, we can honestly say we’ve found the strongest, most reliable trailer locking systems available. If you’re looking for the best trailer coupler lock, the Proven Industries Coupler Lock is the gold standard. This laser-cut steel lock has a unique design that fits over your coupler like a glove, making it impossible to remove even with the help of a pry bar, sledgehammer, and sawzall (there’s literally a video to prove it). If you’re looking for the best trailer hitch lock, the Connor 1615190 has earned the top award. It’s easy to use, incredibly strong, and backed by hundreds of positive experiences. Article Summary

Trailers (and trailer hitches) get stolen all the time. It’s a sad thing to report, but it’s true. We’ve all heard at least one story from a friend or family member who’s fallen victim to the crime. Now, obviously the loss of a 25-foot camper trailer is much more tragic and costly than a simple ball hitch, but theft is still theft all the same. If you ever leave your trailer or hitch unattended (which we all do at some point), it can seriously pay off to invest in a solid locking system to protect it.

Unfortunately, if you’ve done any sort of research into trailer locks already, you’ve probably found that most of them don’t really live up to expectations. Many brands claim their locks are “indestructible”, but actual hands-on testing from customers has shown that most can be cut off with a bolt cutter or simply beaten open with a hammer. With that said, there are a small few brands that have realized this lack of quality and developed unique locking systems that have proven to be durable and trustworthy.

We spent a total of four days researching over 20 trailer locks to figure out which are the toughest and most dependable systems out there. Our research included everything from reviewing materials and designs to talking to manufacturers and customers about their experiences with the durability of each lock. On top of that, we were able to see several hands-on tests to demonstrate the strength of certain locks. After all of our notes were concluded, we’ve found the following three models to be the best trailer locks overall. (jump straight to the best trailer coupler lock or best trailer hitch lock)

Product image of the Proven trailer lock
Product image of the Connor trailer lock
Product image of the MasterLock trailer lock
Proven Industries 2178/2516
Connor USA 1615190
MasterLock 377KA



12 versions available for different coupler sizes and styles (more details)
Fits all Class III/IV 2"x2" and Class V 2.5"x2.5" (5/8" pin)
Fits 1-7/8", 2", and 2-5/16" couplers
Quick Notes
More expensive than others, but well worth the price considering its superior quality and protection
One of the strongest hitch locks available, easy to use, and priced well
Low price offers good bang for your buck, but some tests have proven that this lock can still be broken
1 year

The best trailer coupler lock

When it comes to protecting couplers, the Proven Industries Coupler Lock has become the gold standard in theft prevention. Available in several styles to fit different types of couplers, these locks can easily handle any type of criminal abuse (sledgehammer, bolt cutter, pinch bar, etc.) without breaking.

Proven Industries is a family-owned company that was literally founded on the need for better trailer locks. Their story began when a family trailer with $40,000 worth of equipment was stolen, all because the coupler lock they had in place failed to do its job and was broken off by the thief. When they tried to find a better lock for their new trailer, they realized there was a serious lack of quality locking systems on the market, so they set off to design their own – and the rest, as they say, is history!

Proven coupler locks are made right here in the USA and precision-machined from heavy-duty steel, giving you the highest level of durability possible. But that’s not what makes them so good at their job. As you can see from the image above, these locks have a much more unique design than the average coupler lock. That’s because they’re designed to snugly fit over your coupler “like a glove”, as Proven Industries says. This full-coverage design combined with its ultra-durable material makes the locks virtually impenetrable to the common tools used by thieves. In fact, they’ve been heavily tested under the abuse of sledgehammers, bolt cutters, sawzalls, you name it – and not one has been able to break the lock free. Check out the video demonstration below to see for yourself.

Because of the way this lock slides over the coupler, you may be wondering, “Will this lock fit my specific trailer?” The answer is yes. No matter what trailer you have, Proven Industries has developed nearly a dozen different versions of their lock to fit different coupler styles. Below is a quick rundown of each of their versions to help you choose the right one for your trailer:

2” Couplers (2178 series)
• Model #2178 – this is the most popular version as it’s designed to fit most common trailer couplers, from A-frame welded trailers to straight bolt-on styles.
• Model #2178-A – designed for Atwood Yoke Latch couplers, usually found on open utility trailers or travel trailers.
• Model #2178-B – designed for Bulldog couplers, usually found on more heavy-duty trailers such as commercial or oversized.
• Model #2178-E – designed for raised trigger latch couplers.
• Model #2178-U – designed for UPF couplers, usually found on boat trailers. Can be used with or without surge brakes.
See 2178-series locks here

2 and 5/16” Couplers (2516 series)
• Model #2516 – designed for trigger latch and thumb latch couplers.
• Model #2516-A – designed for Atwood Yoke Latch couplers, usually found on open utility trailers or travel trailers.
• Model #2516-AS – designed for Airstream couplers.
• Model #2516-B – designed for Bulldog couplers, usually found on more heavy-duty trailers such as commercial or oversized.
• Model #2516-B2 – designed for Ram cast steel couplers, usually found on equipment trailers or dump trailers.
• Model #2516-E – designed for Demco couplers, usually found on heavy-duty enclosed vehicle transportation trailers.
• Model #2516-J – designed for Jayco couplers.
See 2516-series locks here

Regardless of which model you choose, most are capable of securing your safety chains, which is a nice benefit that few locks offer. In addition, all come with a lifetime warranty to ensure you’re covered in case something doesn’t fit as planned or you’re having trouble with a part.

Overall, the Proven Industries Coupler Lock has proven its ability to protect trailers from theft better than any other locking system on the market. The only slight downside is its price, but here’s the thing. Would you rather invest a couple hundred dollars into a reliable lock and know with certainty that your equipment is safe? Or would you rather cheap out on a low-grade lock and run the risk of someone stealing your trailer that’s worth $2,000, $10,000, or even $25,000+? At the end of the day, even the most expensive lock is still far cheaper than your trailer, making the investment worth every penny.

The best trailer hitch lock

Truth be told, coupler locks are the bigger worry when it comes to easily breakable units because of how much design can vary. With hitch locks, most designs are fairly similar, so the choice comes down to finding one that’s built with strong material and a great locking mechanism. With that in mind, the Connor 1615190 is what we’ve found to be the best trailer lock out there for keeping your hitch secure.

Connor USA is another company founded on the development of towing accessories. While they don’t focus strictly on lock systems like Proven Industries does (Connor also offers hitches, couplers, and other trailer products), they’ve still managed to earn quite a reputation when it comes to hitch locks. They offer several styles, but the 1615190 model has earned our top pick because it offers convenience and strength unlike the majority of its competitors.

Like most hitch locks, Connor’s unit is designed to slide in through the middle of the receiver (fitting most common setups, including all Class III and IV 2” x 2” and Class V 2.5” x 2.5”). The head of the locking mechanism is on one side, and an oversized cap is on the other. The entire lock is made of solid steel and they’ve specifically focused on minimizing the number of moving parts, so durability is as good as it gets. Speaking of which, Connor has rated it to tow up to 20,000 lbs gross trailer weight, making it one of the strongest hitch locks available.

The locking mechanism is where things are slightly more interesting. As usual, the key goes into the head to unlock the unit – but not to lock it. Connor has designed the system to “auto lock”, so all you need to do to secure it on your receiver is slide it through and push the two sides together until you hear a click. It’s always smart to give it a tug or two once you’ve secured it (like with any lock), but for the most part, you should be good to go. This is especially nice for those who’ve had experience dealing with cheap hitch locks in the past; fumbling around with your keys trying to get them secure has always been a pain. Check out the video demonstration below.

Overall, the Connor 1615190 Hitch Lock is the strongest and most trustworthy option when it comes to hitch and receiver locking systems. In fact, this particular model has earned the title of #1 seller on a variety of different retailers, backed by hundreds of positive customer reviews.

A good bang for your buck

The Proven Industries lock was the only system we found that was truly 100% theft-proof. However, we understand that not everyone thinks it’s worth it to spend several hundred dollars on a lock. In that case, we’d recommend the MasterLock 377KA as the best low-cost alternative. There are some instances where people have proven it can be picked or broken off, but for the most part, it receives positive reviews from customers and will do its part in stumping a good percentage of thieves.

Everyone knows the name MasterLock. They’re arguably the biggest brand in anything lock-related, developing security products since 1921. The 377KA trailer coupler lock is a rather minimalist design compared to other options, but believe it or not, this little unit has received a higher rating of satisfied customer reviews than any of the rest of them (excluding Proven Industries, of course).

Made using a die-cast zinc material, this lock is surprisingly durable for what it is. Its minimalist design makes it very easy to use, and also adds to its ability to protect from theft. Several customers have shown examples of the MasterLock after an attempt to break it with a hammer, and although it’s physically beaten up, it stays secure to the coupler like it’s supposed to.

The biggest issue comes if your thief has a pry bar. Although the lock is durable enough to withstand hammer abuse, the design does have one small opening near the base of the ball where a pry bar can be stuck. With enough leverage and force, a thief can get the base to crack (because it’s die-cast rather than steel), which makes it slip loose from your coupler. If you have some welding experience or can somehow find something else to fill this void, it may perform better, but cracking is a known issue with die-cast materials.

The price is the biggest selling point of the MasterLock 377KA. Cheaper than 95% of the other models out there, no one can deny it offers a great value. However, saving yourself a few bucks now could result in exponentially higher losses later if a thief is able to break it off and steal your trailer, so keep that in mind when deciding whether to buy.

How we picked our top three

There are plenty of trailer locks to choose from these days, whether you’re shopping locally or online. Many advertise fancy words like “indestructible” or “invulnerable”, but when it comes time to prove their abilities, the majority of them fall short. To judge each locking system and figure out which models really were the best trailer locks, we looked at the following aspects.


It should go without saying that a lock’s top quality should be durability. After all, the entire point of a lock is protection, which means being able to withstand any potential damage a burglar might throw at it. Trailer thieves have been known to use all kinds of tools to break open locks, from pry bars and hammers to sawzalls and more.

There are several different qualities that can determine a lock’s ability to withstand damage, but the two most important are its materials and design. Materials are easy to judge – the stronger the metal, the higher the durability. Ideally, we looked for steel or titanium units, as these are the strongest common metals. Design is slightly harder to judge. Ideally, we looked for models that kept the locking mechanism covered and overall didn’t have any large open areas or leverage points. This way, it’s harder for the crooks to break them loose since there’s nowhere to get their tools into.

Ease of use

Trailer locks generally aren’t the most difficult accessories to use, but there’s still a certain level of convenience that’s necessary. Some units have poor locking mechanisms that are difficult to turn and can end up breaking easily if you try to overdo it. This not only plays a role in durability like we spoke about above, but it can also be a serious pain if the mechanism breaks on you when you need it most.

On top of that, some make you go through 10 steps just to secure it to your trailer, and even more when it comes time to unlock it! Although a long unlocking process might sound like it adds to the lock’s ability to prevent theft, that’s unfortunately not true. It doesn’t matter whether there’s one step or 10 steps to unlock it, burglars aren’t following the same steps we are when they’re trying to break your lock off.

With that said, we ideally looked for units that provide quality, user-friendly locking mechanisms to help you avoid both frustration and letdown.


Trailer hitches and couplers come in a wide variety of sizes and styles. In a perfect world, you’ll find a lock that’s been designed with your trailer’s unique specifications in mind (this is one of the reasons we liked the Proven Industries lock so much, they offer nearly a dozen different versions which are each designed to fit a certain size and style). Unfortunately, not every lock is custom fit to your needs, so a lock’s ability to adapt to different specifications without sacrificing its integrity is extremely important. We greatly considered this when looking at both coupler locks and hitch locks alike, making sure that our top picks were suited to handle a wide variety of customer needs while maintaining 100% durability.

Things to consider before buying

Buying a trailer lock isn’t exactly rocket science, but we still think it’s wise to consider a few things to make sure you buy the right model for your needs.

What kind of trailer do you have?

Different trailers have different coupler styles. Commercial trailers usually have Bulldog style couplers, boat trailers usually have UPF couplers, and even different brands can have their own unique couplers like Airstream or Jayco. Most locks are universal and can be fitted to a wide variety of trailers, which works fine at the end of the day – but if possible, we’d recommend trying to find a lock that’s specifically designed to fit the coupler of your exact trailer. This will give it the best probability of remaining intact in the event of a theft attempt since there will likely be less open areas and leverage points.

How much is your trailer (and everything on it) worth?

Everyone’s situation is different. One person may have a little box trailer that isn’t worth much to them, but the next may have a large camper with tens of thousands of dollars of equipment inside (not to mention years of memories). Needless to say, the more your trailer is worth, the more value a good lock has, and vice versa. In other words, it might not be worth it to spend $200 to get the best trailer lock available if your property is only worth $1,000, but to someone whose property is worth $10,000+, then $200 is a small price to pay to keep things safe. Consider your property’s value before deciding how much a lock is worth to you.

How often (and how long) do you leave your trailer unattended?

Some people only leave their trailer unattended for 30 minutes at a time, whereas others leave theirs parked for days, weeks, and even months. If you’re part of the group who only leaves your property unattended for short periods of time, you may be tempted to buy a cheaper lock because you think you’re less at risk to theft. We urge you to reconsider. It doesn’t matter how long your trailer is left unattended, a criminal only needs 5 minutes to strike – and just like that, your stuff will be gone. We personally believe the value of a lock should depend on the value of your trailer, not how long you leave it unattended, so please give that some thought before buying – it’s for your own protection.

Other trailer security systems to consider

Even if you have the best trailer lock in place, there are some thieves who have learned to overlook trailer locks completely and steal trailers by hooking them up with security chains and tow trucks. The chance of this happening is small, but it’s still a chance nonetheless. Thankfully, a trailer lock is not the only security system that can use to protect your belongings in the event of a crime. We’ve listed a few other accessories below that you may want to consider adding to your arsenal of protective systems.

Wheel locks

In the rare event that a burglar does manage to hook your trailer up via tow truck and security chains, that won’t do him or her much good if your wheels are locked too. Wheel locks are the perfect security tool to bring your theft prevention full circle. You’ve got your trailer lock protecting your coupler, and your wheel locks protecting your wheels. There are very few criminals in the world who can get around both, so we’d highly recommend adding them to your trailer if it’s holding anything of substantial value.

GPS tracker

Modern technology gives us eyes and ears wherever we want them, and these days, there are GPS trackers for everything from wallets and keys to cars and trailers. Let’s say you have the misfortune of dealing with a truly skilled criminal who successfully manages to steal your trailer even with your trailer lock still secured to your coupler. If you have a GPS tracker hidden somewhere on board, it doesn’t matter where the thief goes – you’ll always know exactly where he or her is at.


Home security systems using cameras are becoming more and more popular as technology companies make them easier for the average family to setup. For those who’ve never used them before, these cameras, which can be installed anywhere, record a live feed and save it to a place of your choosing. This makes them an excellent tool to install on your trailer, best angled towards your coupler. If someone tries to steal your trailer, whether they are successful or not, you’ll have a clear image of what they look like to send to your local authorities.

For those who want even more ideas on theft prevention, Trail Rider Magazine created a list with some other interesting ways to keep your trailer protected.

Wrapping it up

If you’re going to take one thing from this guide, let it be this – according to combined reports from the CHP and FBI, over 25,000 trailers are stolen each year, with estimated losses over $10 billion. Don’t become another statistic on their list. A truly foolproof lock may be expensive, but it’s an investment that will pay itself off ten times over if it stops even one theft attempt on your trailer.

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