The HoldUp features StrongArm technology to protect bikes and allows for fast and easy loading.⋅ Side-to-side adjustability that reduces bike to bike interference ⋅ StrongArm design fits wheels from 20-29" ⋅ Zero contact with the bike frame ⋅ Tilts down with bikes loaded for rear of vehicle access ⋅ Compact design allows the bike trays to fold up when not in use ⋅ Comes with fully integrated security; Locks bike to rack and rack to vehicle (SKS LOCK CORES included). ⋅ Carries 2 bikes out of the box, or 4 bikes with optional HoldUp +2 (AR7288)