Master Lock Co 377KA-0313 Trailer Coupler Lock

Product Description

The MASTER LOCK CO 377KA-0313 is a trailer coupler lock engineered to secure trailer couplers during storage or transport. The advanced locking mechanism is built to resist picking and prying, providing a physical deterrent against unauthorized trailer movement. It fits 1-7/8 inch (48mm), 2 inch (51mm), and most 2-5/16 inch (59mm) couplers, covering the most common coupler sizes in use on light-duty and utility trailers. The lock is keyed alike to key code 0313, making it well-suited for fleet applications where a single key controls multiple locks. Compatible key blanks are the Master Lock K1BOX or Ilco blank M1 TV 320-952.

This coupler lock is used by fleet operators, transportation crews, contractors, and property managers to prevent trailer theft when a tow vehicle is disconnected. It installs directly onto the coupler ball socket and requires no tools for attachment. The keyed-alike feature is particularly useful for operations managing multiple trailers, as it reduces the number of keys a technician or driver must carry on the job.

Key Features

• Fits 1-7/8 inch, 2 inch, and most 2-5/16 inch trailer couplers
• Advanced locking mechanism resists picking and prying
• Keyed alike to code 0313 for multi-lock fleet use
• Compatible with Master Lock key blank K1BOX and Ilco blank M1 TV 320-952
• Sold in a package quantity of 4 units

Compatibility

Designed to fit 1-7/8 inch (48mm), 2 inch (51mm), and most 2-5/16 inch (59mm) trailer couplers commonly found on light-duty utility, landscape, and equipment trailers.

Installation Notes

No tools are required to install this coupler lock onto a standard ball socket coupler. Ensure the coupler latch is fully open before seating the lock body, then engage the locking mechanism and confirm it is fully locked before releasing the trailer. Inspect the lock body for wear or damage periodically, especially in high-use fleet environments. This product does not substitute for proper trailer hitch safety chains or other federally required towing safety equipment.

Technical Specifications

• Coupler Fit: 1-7/8 inches (48mm), 2 inches (51mm), most 2-5/16 inches (59mm)
• Key Code: 0313 (Keyed Alike)
• Compatible Key Blanks: Master Lock K1BOX, Ilco M1 TV 320-952
• Package Quantity: 4 EA
• Weight: 14 pounds

Standard Information

• Brand: MASTER LOCK CO
• Manufacturer Part Number: 377KA-0313