This trailer hitch receiver lock is manufactured by Trimax. It fits your Class II receiver hitches (1 1/4" x 1 1/4") with a 1/2" diameter hitch pin hole. This is the most common lock to secure your ball mount to your hitch on your vehicle. This is Trimax part number TR125. It is made of solid steel, chrome plated and features a rubber flap to keep the key entry clean. Heavy duty class II Rated. This Locking Hitch Pin is ideal for maintaining security while towing and parking your trailer. The Locking Portion of the head features an easy 1/4 Turn Function for locking and unlocking. The Water Tight head helps keeps dirt and debris from entering the locking chamber.