Master Lock trailer coupler locks 2-pack — Fits 1-7/8", 2", 2-5/16" couplers, weather-resistant red finish

Whether you store a utility trailer, travel trailer, or boat dolly, the Master Lock 389DAT two-pack provides a practical security solution that fits the common coupler sizes used across the U.S. and Europe. Engineered to resist tampering and the elements, these locks are quick to install and remove while their bright finish acts as a visible theft deterrent. The set includes two locks that are keyed differently for flexibility when protecting multiple trailers.

What coupler sizes does this lock fit?

This coupler lock accommodates the most frequently used ball-diameter standards: 1-7/8" (48 mm), 2" (51 mm), and 2-5/16" (59 mm). An internal adjustable mechanism allows the lock to clamp securely around the coupler throat so it works across those sizes without adapters.

• Compatible with 1-7/8", 2" and 2-5/16" couplers
• Internal fitment adapts to several common sleeve diameters
• No extra parts required for standard trailer couplers

How does it resist theft and tampering?

The 389DAT uses an advanced locking cylinder and a robust body that make picking and prying more difficult than basic locks. The visible red finish serves as a psychological deterrent, reducing the chance a thief will attempt to steal or move the trailer.

• Anti-pick locking mechanism increases resistance to manipulation
• Solid construction discourages levering and forced entry
• High-visibility color deters opportunistic thieves

Is it durable in wet or salty environments?

These locks are built to withstand exposure to moisture and road salts so they keep working during seasonal use. Corrosion-resistant materials and finishes reduce the risk of rust, making them suitable for trailers stored outdoors or used near water.

• Corrosion-resistant body and finish extend service life
• Designed for repeated outdoor use without seizing
• Easy to clean and maintain after exposure to road grime

How easy is installation and keying?

Installation takes only a few seconds: place the lock over the coupler throat and turn in the key to engage. This two-pack contains locks keyed differently, so each unit has its own unique key—useful when securing multiple trailers or keeping one as a spare.

• Tool-free installation and removal in seconds
• Each lock has a unique key number—locks are not keyed alike
• Compact form factor stores easily when not in use

Who this product is for: The Master Lock 389DAT two-pack is ideal for trailer owners who need a straightforward, reliable way to prevent tow-away theft and unauthorized use. It suits occasional users who want an easy-to-handle lock, fleet managers who need consistent, visible security across multiple trailers, and boat or RV owners who store their equipment outdoors. If you want a weather-resistant, quick-install coupler lock that fits the most common trailer sizes and gives clear visual deterrence, this Master Lock set is a practical choice.