Fits 1-7/8 and 2 ball. Great additions to any standard 2 box style receiver hitch. The Triple or Double Ball mount gives you the convenience of easily changing your ball size for the times you have multiple trailer use. The Drop Mounts are needed to level out your trailer with your vehicle. They have a 1 Ball Shank Hole to fit the Curt Chrome Ball assemblies or any ball with a 1 diameter shank. Don't forget your Safety Chains to secure your trailer to your receiver hitch. Maybe the vehicle or trailer you are towing doesn't have any lights, these Magnetic Auxiliary Towing Lights will come in mighty handy in that case. The Rubber Hitch Ball Cover is an inexpensive way to keep that chrome hitch ball from rusting when not in use. All the Ball mounts are Gloss Black Powder coated.