Lock the Coupler or the Receiver? Best Trailer Hitch Lock Options for Boats and Campers

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The best trailer hitch lock depends on where the trailer is when you walk away from it. A boat trailer or camper parked in the driveway needs a coupler lock that fills the ball socket so nobody can drop it onto their own hitch. A trailer still hitched to your truck needs a locking receiver pin, and often a latch pin on the coupler too.

We compared seven locks, every one in stock and sold by Amazon.com or the brand’s own store: a keyed-alike coupler kit, three ball-style coupler locks, two receiver pin locks, a keyed-alike pin set and a small latch pin. For each we list the ball sizes, pin diameter, receiver class and warranty wording exactly as the listing states them, and we treat strength or pick-resistance claims as the brand’s words.

No lock makes a trailer theft-proof. These make it slower and more visible to steal, which is the point. Measure your coupler and receiver before you order, because fit is where most returns start.

Our Top Trailer Hitch Lock Picks at a Glance

Price key: $ under $50 · $$ $50–$100 · $$$ $100–$175 · $$$$ $175+. Prices change often; check Amazon for today’s price.

1. Rhino USA Coupler Lock Kit (2-5/16 in): Best Overall Coupler Lock Set

Rhino USA’s Coupler Lock Kit pairs two locks in one box: a coupler lock that sits in the trailer’s ball socket and a pin lock for the tongue latch. Both open with the same key, and two matching keys come in the package. This version is sized for 2-5/16 inch couplers; Rhino lists a separate kit for 2 inch trailers.

Fit is spelled out in detail. The listing says the coupler lock fits 2-5/16 inch A-frame, 50×50 and 50×60 couplers, with a maximum lip width of 4-3/8 inches and a maximum lip height of 5/16 inch. It is not for rolled-lip or underslung designs, and the latch lock is meant for standard tongue latches. Check those numbers against your trailer before ordering.

Day to day, you drop the trailer, slide the coupler lock into the empty socket, lock it, and run the pin through the latch. Rhino calls it tamper-resistant and anti-theft steel, and says a heavy-duty powder-coated finish shields against rust, corrosion and harsh weather. The listing names boat trailers, RVs, toy haulers and campers stored at home or on a job site. Rhino describes itself as a family-run American company and offers what it calls a real lifetime replacement.

It suits anyone storing a 2-5/16 inch trailer for weeks at a time, especially boat and camper owners who want both theft points covered without carrying two keys.

Why we like it

• Coupler and latch on one key
• Detailed fit limits on the listing
• Lifetime replacement policy

Watch out for

Measure your coupler lip first: the listing caps width at 4-3/8 inches and rules out rolled-lip and underslung couplers.

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2. Rhino USA 2 in Locking Hitch Pin: Best Receiver Hitch Pin Lock

A receiver pin lock replaces the plain hitch pin and clip that hold a ball mount in your truck’s receiver. Rhino USA’s 2 inch Locking Hitch Pin does that job with a keyed lock on one end, so the ball mount, bike rack or cargo carrier can’t simply be pulled out while you’re parked.

The listing says it fits all Class III and IV hitches with a 2 by 2 inch receiver. That covers most full-size pickups and many SUVs, but check the class stamped on your hitch. Owners of 2.5 inch Class V receivers need Rhino’s separate 2.5 inch pin, which that listing gives as 5/8 inch in diameter. This 2 inch listing doesn’t state the pin diameter, so confirm it fits your receiver’s cross hole.

The feature Rhino highlights is a patented slide cap, a weatherproof cover meant to block dirt, mud and debris from the lock. That matters on a pin that rides just above the road and gets sprayed with slush and salt all winter. Rhino says the pin is made from solid steel with a tamper-resistant design, and backs it with the same lifetime replacement promise as its other products.

It suits anyone who leaves a ball mount in the receiver between trips, or who tows to a ramp or campsite and steps away from the rig while it’s still hitched.

Why we like it

• Top seller in Hitch Locks
• Sliding weather cap
• Lifetime replacement

Watch out for

The listing doesn’t give the pin diameter, so confirm it matches your receiver before relying on it.

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3. Master Lock 379ATPY Coupler Lock: Best Universal Coupler Lock

Master Lock’s 379ATPY is a universal trailer coupler lock: a block that sits in the coupler’s ball socket so the trailer can’t be dropped onto another vehicle’s ball. One lock covers three common sizes, which is handy when the boat trailer and the utility trailer don’t share a ball.

The listing says it fits 1-7/8 inch, 2 inch and most 2-5/16 inch trailer couplers, and Master Lock’s own product page uses the same wording. Note the word “most” on the largest size. The body is zinc, which Master Lock says helps it stand up to outdoor storage, boat ramps, campsites and job sites. The brand also says its locking mechanism is engineered to resist picking and prying.

In use, it’s a simple drop-in-and-lock design with no latch pin or second piece. Master Lock calls installation and removal simple, and two keys come in the package. The manufacturer’s page describes this model as keyed different, so it won’t share a key with other locks you own unless you buy a keyed-alike product.

It suits trailer owners who want one lock that moves between trailers, such as a boat trailer in summer and a utility trailer in fall, and anyone who prefers buying a lock shipped and sold by Amazon.com. At a listed 1 pound, it is easy to toss in a truck box between uses.

Why we like it

• Three ball sizes in one lock
• Sold by Amazon.com
• Compact, 1 lb listed weight

Watch out for

Fit on 2-5/16 inch couplers is listed as “most,” not all, and there’s no latch lock in the package.

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4. RETRUE Heavy-Duty Universal Coupler Lock: Best Adjustable Coupler Lock

RETRUE’s Heavy-Duty Universal Coupler Lock uses a ratcheting U-shaped shackle that wraps around the coupler and locks at one of 11 positions. Because it adjusts, one lock fits 1-7/8, 2 and 2-5/16 inch couplers, according to the listing.

RETRUE pitches it as the heavier of its two lines. The brand says it uses a wider and thicker steel U-shaped pipe and body for more resistance to external force, built from an aluminum body and high-strength A36 steel that RETRUE says resists cutting and shearing. It is described as rustproof and weatherproof. The lock cylinder is listed as upgraded with a more complex mechanism and thicker keys; RETRUE calls it virtually impossible to crack, which is a marketing claim rather than a tested rating.

Daily use is quick: slide the shackle through the coupler, ratchet it down snug and turn the key. The listing describes it as “QC product quality certified,” wording that doesn’t name a standard or an outside testing body. RETRUE’s bullets promise a 120-day warranty and 24/7 support through Amazon’s “Ask a Question” button, while the warranty field reads one year, so keep your receipt and ask the seller which applies.

It suits owners with more than one trailer who want a sturdier universal lock than the slim budget versions, and who are comfortable with a brand-run storefront rather than Amazon.com.

Why we like it

• Ratchets to fit three ball sizes
• Thicker shackle than RETRUE’s budget lock
• Bright, visible design

Watch out for

The warranty wording conflicts between the bullets and the warranty field, and the listing gives no size or weight.

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5. TowWorks 79632 Keyed-Alike Pin Locks (2-Pack): Best Keyed-Alike Pin Set

TowWorks sells the 79632 as a pair of receiver pin locks that share one key. Each is a 5/8 inch pin with what TowWorks calls an extra-long maximum active length of 3-1/4 inches, which lets it reach across both 2 inch and 2-1/2 inch Class III and IV receivers.

The listing is unusually frank about fit. It says the lock does not fit CURT channel-style adjustable hitches 45900, 45901 and 45902, CURT adjustable pintle hooks 45907 and 45908, Andersen Rapid Hitch kits or FASTWAY adjustable hitches, and it asks buyers to verify every dimension first. Rubber O-rings help keep the pin from rattling, and TowWorks says to add or remove O-rings to suit different receiver tubes.

Locking is push-to-lock with a 1/4-turn tubular key, and a rubber dust cap covers the keyway. A separate R spring clip, or cotter pin, rides through the pin as a backup; TowWorks says it must be inserted whenever you use the lock, and that the pin can be used with or without the lock mechanism. The warranty field reads one year on the lock finish and lifetime on lock function. If you need three or four keyed-alike locks, TowWorks lists models 79633 and 79634.

It suits families with two trucks, or anyone securing a ball mount in one receiver and a cargo carrier in another without juggling keys.

Why we like it

• Two locks on one key
• Spring clip backup
• Clear list of incompatible hitches

Watch out for

Check the do-not-fit list against your hitch, and always insert the spring clip as TowWorks instructs.

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6. CZC AUTO 11302 Swivel-Head Pin Lock: Best Bent-Pin Receiver Lock

CZC AUTO’s 11302 is a bent, padlock-style receiver pin lock. The pin is 5/8 inch in diameter with a 3-1/2 inch effective length, and the listing says it fits Class III and IV hitches with 2 or 2-1/2 inch receiver tubes. CZC AUTO asks buyers to check their hitch setup before ordering.

Locking takes no key. Push the head onto the pin until it clicks, then tug it to confirm it caught. To open, a quarter turn of the key pops the pin up on its own, according to the listing. The head swivels, which makes it easier to line up and handle when the receiver sits low or is tucked behind a bumper.

CZC AUTO describes the pin as chrome-plated high-strength steel to deter theft and corrosion, and a cap keeps moisture, dust and rust out of the keyhole. Beyond trailers, the brand lists uses with ball mounts, hitch racks, cargo trays, bike racks and tow ropes. The bullets promise a 30-day money-back window for any reason and a 12-month warranty for quality-related issues, though the warranty field itself is empty.

It suits anyone who wants a simple locking pin at a low cost, including drivers who keep a bike rack or cargo tray in the receiver most of the year.

Why we like it

• Locks without the key
• Swivel head
• Fits 2 and 2-1/2 in receivers

Watch out for

Sales rank is the lowest on this page, and the specs file leaves warranty, size and weight blank.

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7. RETRUE RTL200 Tongue Latch Lock: Best Latch Pin Lock

RETRUE’s RTL200 is a small padlock-style lock with a 1/4 inch pin that passes through the hole in a coupler’s latch. Once it’s in, the latch can’t be lifted, so the coupler can’t be released from the ball while the trailer is hitched. The listing says it fits latch-type couplers with a span of up to 3/4 inch.

Materials are described two ways. One bullet says the body is high-strength zinc alloy with a black painted finish and the pin is zinc-plated against corrosion; another says the lock is made from high-strength steel. Treat the build description as the brand’s wording. The operating instructions also mix terms: RETRUE mentions a simple 1/4-turn activation and, in the same bullet, says to spin the flat key five to seven times to open or close it.

At a listed 0.36 pounds and about two inches across, it stays out of the way during towing and fits in a glove box when it isn’t on the trailer. Two keys come in the package, and RETRUE offers support through Amazon’s “Ask a Question” button.

It suits anyone who already locks the receiver and wants the coupler latch closed too, for example at a boat ramp, campsite or fuel stop.

Why we like it

• Tiny and light
• Strong Hitch Locks rank
• Pairs well with a receiver pin lock

Watch out for

A latch pin doesn’t block the ball socket, so it isn’t a substitute for a coupler lock on an unhitched, parked trailer.

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How We Chose the Best Trailer Hitch Locks

We started with listings that were in stock and sold by Amazon.com or the brand’s own storefront, then compared what each listing actually states:

• Lock type: coupler lock for a parked trailer, receiver pin lock for the tow vehicle, or a latch pin for the coupler.
• Fit as listed: ball sizes (1-7/8, 2 or 2-5/16 inch), pin diameter, effective pin length and receiver class.
• Weather protection: caps, slide covers and finishes that keep grit and water out of the keyway.
• Keying: whether locks share a key, and how many keys come in the box.
• Evidence: Amazon sales rank, seller and the warranty field, with gaps flagged.

Every pick happened to land in our lowest price tier, so this guide is a spread of lock types rather than prices. We capped brands at two picks, and only where the two products are different kinds of lock.

Trailer Hitch Lock Buying Guide

Best Coupler Lock for a Parked Trailer

A coupler lock fills or blocks the ball socket on the trailer tongue so it can’t be lowered onto someone else’s hitch ball. That’s the lock to use whenever the trailer sits unhitched in a driveway, storage lot or job site. Fixed-size locks like the Rhino USA kit are sized to one ball, while universal designs such as the Master Lock 379ATPY and RETRUE’s ratcheting lock cover 1-7/8, 2 and 2-5/16 inch couplers. Master Lock’s 379ATPY product page repeats that it fits 1-7/8 inch, 2 inch and most 2-5/16 inch couplers.

Best Trailer Coupler Lock for a Boat Trailer

Boat trailers spend time at ramps and in wet storage, so look for a finish meant for weather and a lock you can work with wet hands. Check the ball size stamped on your coupler first; the Rhino USA kit comes in separate 2 and 2-5/16 inch versions, and its listing rules out rolled-lip and underslung couplers. If you keep the boat on the river, our guide to boat insurance on the Ohio River covers the coverage questions to raise with your agent.

Best Hitch Pin Lock: Pin Diameter and Length

Receiver pins are sized to the hitch class. Our receiver picks list 5/8 inch pins for 2 and 2-1/2 inch Class III and IV receivers; the Rhino USA 2 inch listing doesn’t state a diameter. None of our picks is sold for smaller Class I or II receivers, which may take a different pin size, so check the class stamped on your hitch and measure the pin hole before ordering. Effective pin length matters too: the CZC AUTO lists 3-1/2 inches and the TowWorks 3-1/4 inches, enough to span a 2-1/2 inch receiver.

Best Receiver Hitch Lock for Hitch Racks and Ball Mounts

A locking receiver pin keeps a ball mount, bike rack or cargo carrier from sliding out of the receiver while you’re parked. Push-to-lock designs (CZC AUTO, TowWorks) let you lock without the key, and slide caps or rubber caps keep road grime out of the cylinder. O-rings on some pins also cut rattle, according to the listings.

Best Trailer Lock Set

Sets save keys. The Rhino USA kit pairs a coupler lock with a latch lock on one key, and the TowWorks 79632 gives two receiver pins on one key. If you want a coupler lock, a receiver pin and a latch pin all keyed alike, you’ll need to buy a set built that way; mixing brands means mixing keys.

Trailer Theft, Tracking and Your Auto Coverage

Ohio ranked sixth among states for total motor vehicle thefts in 2025, with 20,628 reported, according to National Insurance Crime Bureau figures compiled in the Triple-I auto theft facts page. A lock is one layer. Parking the trailer out of easy reach, chaining a wheel, keeping photos and serial numbers on file and adding a tracker all help; our guide to the best GPS tracker for a car covers trackers for recovering your own vehicle or trailer.

How a stolen or damaged trailer is handled depends on your policy and how the trailer is insured. A lock doesn’t change your rate or guarantee a claim outcome, so ask your agent how your trailer, boat or camper is covered. Start with our guides to travel trailer insurance in Ohio and car insurance in Portsmouth, Ohio.

Frequently Asked Questions

What is the best coupler lock for a parked trailer?

Our top pick is the Rhino USA Coupler Lock Kit, which pairs a coupler lock with a latch lock on one key and lists fit for 2-5/16 inch A-frame, 50×50 and 50×60 couplers. If you need one lock for several ball sizes, the Master Lock 379ATPY lists 1-7/8, 2 and most 2-5/16 inch couplers.

What size hitch pin lock do I need?

Match the pin to your receiver. Our receiver picks list 5/8 inch pins for Class III and IV hitches with 2 or 2-1/2 inch receivers. Check the class on your hitch and the effective pin length; the TowWorks lists 3-1/4 inches and the CZC AUTO 3-1/2 inches.

Is a latch pin lock enough to stop trailer theft?

Not on its own for a parked trailer. A latch pin like the RETRUE RTL200 keeps the coupler latch closed on a hitched trailer, but it doesn’t fill the ball socket. For an unhitched trailer, use a coupler lock.

What is the best trailer coupler lock for a boat trailer?

Check the ball size on your coupler first. The Rhino USA kit names boat trailers and comes in 2 and 2-5/16 inch versions with a powder-coated finish. The Master Lock 379ATPY lists boat ramps among its uses and fits three ball sizes.

Will a trailer hitch lock lower my insurance?

Don’t count on it. A lock is a theft deterrent, not a guaranteed discount or claim outcome. Ask your agent how your trailer, boat or camper is covered and whether any security device matters on your policy.

The Bottom Line

For a parked trailer, the Rhino USA Coupler Lock Kit is the best trailer hitch lock to start with: a coupler lock and latch lock on one key, with detailed fit limits on the listing. The Master Lock 379ATPY covers three ball sizes from Amazon.com, and RETRUE’s heavy-duty lock ratchets to fit with a thicker shackle. On the tow vehicle, the Rhino USA 2 inch pin leads the Hitch Locks rankings, the TowWorks 79632 puts two pins on one key, and the CZC AUTO is a simple push-to-lock pin. Add the RETRUE RTL200 to lock the latch while you’re hitched.

Want to know how your trailer, boat or camper is covered before you leave it parked? Call Jeff Smith’s State Farm office at (740) 354-7747 or get a free coverage review, and ask your agent how your policy applies.