Designed with new locking solutionNo need to insert key when locking pin into lock head for easy and convenient operation. Heavy-duty solid steel pin construction for superior strength and durability. Designed to fit most common hitch setups: 1/2 in. Dia pin fits Class I and II 1-1/4 in. x 1-1/4 in. hitch receivers while 5/8 in. Dia pin fits Class III, IV and V receivers. Material/Surface: rugged carbon steel with chrome finish. Included 2 flat keys and an all-weather rubber key slot cap to protect keyhole from outside elements. Lock head has diamond machined knurled finish for better grip. Universal use: designed to fit Class I, Class II, Class III, Class IV and Class V hitch receivers. Please make sure pin is pushed all the way in into locking head to click and make sure its completely locked.