Master Lock Trailer Coupler Lock 389DAT Universal 1-7/8"–2-5/16" Red, Visible Tamper-Deterrent

The Master Lock 389DAT is a universal trailer coupler lock engineered to secure 1-7/8", 2" and 2-5/16" couplers with a visible, tamper-deterring design.

Whether you're parking a utility trailer, boat trailer or equipment hauler, the Master Lock 389DAT gives you an easy-to-install physical barrier that fits the most common coupler sizes. Built to stand up to daily exposure, its bright finish acts as a visual deterrent while the internal locking components are made to resist picking and prying. The unit is backed by Master Lock's Limited Lifetime Warranty for long-term ownership confidence.

How does this lock fit different trailer couplers?

The 389DAT is made to accommodate the three most common coupler diameters—1-7/8" (48mm), 2" (51mm) and 2-5/16" (59mm)—so one lock covers multiple trailers. Its adjustable design and streamlined shape slide into the coupler throat and lock in place without extra tools.

• Universal sizing for three standard coupler diameters
• Simple slide-and-lock installation
• Works with ball-type couplers common on utility and boat trailers

What protects the lock from theft attempts and weather?

The internal locking mechanism is engineered to resist common attacks like picking and prying, while the outer finish helps protect the body from rust and corrosion. The bright red color also provides a clear visual cue to would-be thieves, reducing casual tampering.

• Advanced internal mechanism deters picking and prying
• Corrosion-resistant finish for outdoor durability
• High-visibility color functions as a theft deterrent

How easy is it to install and remove on a routine basis?

Installation is tool-free: insert the lock into the coupler and engage the locking pin until it clicks. Removal is equally straightforward—unlock with the key and withdraw—so you can secure or release your trailer quickly at the dock, job site or storage lot.

• Tool-free installation and removal
• Quick locking and unlocking with included keys
• Compact design that stores easily when not in use

What kind of warranty and support does Master Lock provide?

Master Lock stands behind the 389DAT with a Limited Lifetime Warranty that covers defects in materials and workmanship. This warranty gives you recourse if the lock fails under normal use, plus access to Master Lock customer support for product questions.

• Limited Lifetime Warranty for manufacturing defects
• Customer support through Master Lock for troubleshooting
• Replacement guidance available if keys are lost (subject to policy)

Who this is for: The Master Lock 389DAT is ideal for trailer owners who want a single, easy-to-use lock that fits the most common coupler sizes. It's a good choice for boat owners, contractors, landscapers and anyone who stores trailers in shared or public spaces and wants a visible, durable deterrent with reliable everyday function.