1. 1/2 inch and 5/8 inch Hitch Pin Lock Set recommended for all 1-1/4 inch, 2 inch trailer hitch and 2-1/2 inch trailer receiver lock. Trailer Lock Set with Extended shaft of 3-1/2 inch also fits most trucks with heavy-duty tow packages. 2. Extra safety clip & hole in each hitch lock pin for towing when locking system is lost or damaged. Locking pin for trailer hitch with 10 silicone O-rings for a perfect fit. 3. Easy to use lockable hitch pin: locking hitch pin for 2 inch receivers and more made easy to install with Push-to-lock technology. Equally easy to unlock hitch locking pin with just 1/4 key turn system. 4. Material: zinc alloy 5. Scope of application: RV Truck Trailer RV Construction Vehicle Camper