Master Lock Universal Trailer Coupler Locks, 2-Pack (Fits 1-7/8"/2"/2-5/16") Red, Corrosion-Resistant

Master Lock's #389DAT universal coupler locks are a two-pack of keyed-different security devices made to fit most 1-7/8", 2", and 2-5/16" trailer couplers for on-trailer protection.

These coupler locks provide a straightforward physical barrier that helps prevent unauthorized hookups and discourages opportunistic thieves. Built to fit the common 48 mm (1-7/8"), 51 mm (2"), and 59 mm (2-5/16") coupler sizes, the pair arrives keyed differently so each lock uses its own key. The locks combine a visible deterrent finish with an internal mechanism designed to resist picking and prying, plus corrosion-resistant materials for longer outdoor life.

How does this lock fit different trailer couplers?

The #389DAT uses a universal shape and adjustable interface to match the most common coupler diameters without extra adapters. It slides into the coupler throat and secures across the opening so the trailer cannot be attached to a ball hitch while locked.

• Fits 1-7/8" (48 mm), 2" (51 mm) and 2-5/16" (59 mm) couplers.
• Simple slide-and-lock installation with no tools required.
• Works with most standard trailer coupler designs.
• Sold as a two-pack with different keys for each lock.

What security features are built into these coupler locks?

Master Lock engineered the internal locking components to resist common attacks such as picking and basic leverage attempts. The bright red finish increases visibility, which can deter tampering before it starts.

• Advanced locking mechanism to make picking more difficult.
• Solid construction that resists basic prying forces.
• High-visibility red finish discourages casual interference.
• Differently keyed pair reduces risk if one key is copied or lost.

Will these locks hold up outdoors and in salty conditions?

Materials and coatings were selected to slow rust and corrosion so the locks remain functional when left on trailers. Routine care—wiping off road salt and lubricating the lock mechanism occasionally—extends service life even further.

• Corrosion-resistant finish to resist weather exposure.
• Sealed components reduce internal moisture intrusion.
• Easy to clean after wet or salty use; occasional lubrication recommended.

How easy are they to install and carry?

Installation takes seconds: slide the lock into the coupler opening and close the mechanism. The compact, lightweight form keeps the locks portable so you can store them in the vehicle or on-board when not in use.

• Tool-free installation and removal in moments.
• Compact size fits in glove compartments or tool boxes.
• Two keys included for each lock; keys are not identical between the pair.

Who is this for: Owners of small trailers, utility trailers, boat trailers, and other towable equipment who want a visible, low-effort way to block unauthorized connections. These Master Lock #389DAT coupler locks suit anyone who prefers a universal, weather-resistant option that fits the most common coupler sizes and is quick to use when loading, parking, or storing a trailer.