We offer several different Hitch Tighteners here at Hollywood Racks. This Hitch Tightener uses a U Bolt and Bar system that compresses the bike rack onto your vehicles hitch, using the flange. This fits both the 1.25" & 2" Hitches. Specifications for the Hitch Tightener: U-Bolt fits both 1.25" & 2” hitches (qty = one) Clamp Bar (qty = one) Split Washers (qty = two) Flat Washers (qty = two) ½-13 Hex Nuts (qty = four) Installation Installation Instructions