5/8 COUPLING PIN LOCK SET RECOMMENDED FOR - Extra long hitch pin with 5/8 diameter and 3-1/2 maximum working length, fits Class III, IV, V 2, 2.5 and 3 inch receiver. (Please check your hitch size and get a suitable hitch pin lock) MORE STURDY AND DURABLE - The hitch trailer is made of heavy duty iron and finished with black electroplating to increase resistance to damage. wear and rust. The waterproof dust cap can protect the keyhole from water and dirt. Comes with spring clip and 5 rubber O-rings - 1. A separate spring clip and 2 holes provide security Additional 2 clip holes, one for 2" x 2" receivers, the other for 2.5" x 2.5" receivers. 2. Rubber O-rings prevent rattling and keep the clutch pin in place. PUSH-LOCK DESIGN MAKES USER-FRIENDLY - With push-to-lock and 1/4-turn technology, it's easy to lock and unlock the hitch lock assembly. Unlike most plain locks, our Plum Blossom Lock Core upgraded aluminum alloy round key is much harder to pick than flat keys for added security.