Master Lock 378DAT Adjustable Universal Coupler Lock

Product Description

The MASTER LOCK 378DAT is an adjustable universal coupler lock designed to secure trailer hitches against unauthorized attachment and theft. It fits 2-5/16 inches trailer couplers and installs or removes without tools, making it practical for field use. The advanced locking mechanism is engineered to resist picking and prying, providing a higher level of physical security than standard padlock-style deterrents. The lock body is built to resist rust and corrosion, making it suitable for outdoor and all-weather storage conditions. This type of coupler lock is a standard security measure used by transport, landscaping, and general trade contractors who store trailers on job sites or in unsecured lots.

The 378DAT is intended for use on trailers equipped with 2-5/16 inches ball couplers, the size commonly found on medium to heavy-duty utility, equipment, and cargo trailers. It is well suited for residential and light commercial applications where trailer theft is a concern. The adjustable universal fit means it can be applied across a range of coupler brands and styles without requiring additional adapters or hardware.

Key Features

• Fits 2-5/16 inches trailer couplers for a secure, snug fit
• Adjustable universal design accommodates a range of coupler brands and styles
• Advanced locking mechanism resists picking and prying
• Corrosion-resistant construction for outdoor and all-weather use
• Tool-free installation and removal for fast deployment in the field

Compatibility

Designed as an OEM-style replacement and universal fit for trailers equipped with 2-5/16 inches ball couplers across a wide range of utility, cargo, and equipment trailer manufacturers.

Installation Notes

Coupler locks of this type are installed by the trailer owner or operator and require no special tools. Before installing, confirm the trailer is unhitched and the coupler is fully closed. Verify the coupler diameter matches 2-5/16 inches before applying the lock. Remove the lock and inspect for wear or damage at regular intervals to ensure continued function.

Technical Specifications

• Coupler Fit: 2-5/16 inches
• Weight: 3.22 pounds
• UPC: 71649213236
• Sold As: Each

Standard Information

• Brand: MASTER LOCK
• Manufacturer Part Number: 378DAT