Master Lock Coupler & Ball Mount Locks

Master Lock Coupler & Ball Mount Locks: Purpose-Built Trailer Security

When a trailer, camper, or boat is sitting in a parking lot or driveway, it becomes a target. Master Lock has been engineering security solutions since 1921, and their line of coupler & ball mount locks brings that century of expertise directly to trailer protection — combining durable construction, tamper-resistant mechanisms, and weather-hardened materials into products built for life on the road.

What Makes Master Lock Stand Out in Trailer Security

Master Lock approaches coupler and ball mount security with a layered philosophy. Trailer coupler locks are designed to clamp over the hitch ball to prevent a trailer from being hitched to an unauthorized vehicle and towed away — addressing one of the most common forms of trailer theft. Their lineup covers a wide range of coupler sizes, and standout models like the 379DAT offer universal fitment, designed to fit 1-7/8 in., 2 in., and most 2-5/16 in. couplers.

For those who need even more flexibility, the 2847DAT features an adjustable stainless steel latch with six locking positions ranging from 9/16 in. to 2-3/4 in., making it compatible with a wide variety of coupler trigger-latch designs — whether the trailer is hitched or parked. The stainless steel construction is built to resist rust and corrosion, a critical consideration for boat trailers and marine environments.

Advanced Locking Mechanisms for Real-World Threats

Master Lock coupler locks aren't just about fitting the hardware — they're engineered to resist the tactics thieves actually use. The locking mechanisms found across their trailer security line are specifically designed to resist picking and prying, two of the most common attack methods. Keyway covers on many models protect the locking cylinder from moisture and dirt accumulation, preserving function even after extended exposure to road spray, salt, and weather.

For trailer owners who want comprehensive coverage, Master Lock also offers keyed-alike combo sets — such as the ML44VR — that bundle a coupler ball lock, a locking hitch pin, and a coupler latch lock, all operated by a single key. This eliminates the hassle of managing multiple keys while ensuring every vulnerable connection point on the hitch system is protected simultaneously.

A Trusted Name Backed by a Limited Lifetime Warranty

One of the most compelling reasons to choose Master Lock in this category is their commitment to standing behind their products. Select coupler lock models carry a Limited Lifetime Warranty, offering long-term peace of mind for an investment that guards far more valuable assets — whether that's a utility trailer, an RV, or a boat on a custom trailer. With over 100 years as "the authentic, enduring name in locks," Master Lock brings credibility and proven durability to every product in their towing security lineup.

• Universal coupler locks fitting 1-7/8 in., 2 in., and 2-5/16 in. coupler sizes
• Adjustable stainless steel latch designs for flexible, multi-position fitment
• Advanced locking mechanisms engineered to resist picking and prying
• Keyway covers that guard against moisture, dirt, and corrosion
• Keyed-alike combo sets for full hitch system protection with one key
• Limited Lifetime Warranty on select models

Browse the full selection of coupler & ball mount locks or explore everything Master Lock offers across towing, outdoor, and vehicle security categories.