The Strong Arm* Technology Of This Premium Tray Mount Protects Your Bikes And Lets You Load Each One In 10 Seconds Or Less. So You're Guaranteed A Speedy Escape In Your Getaway Car. Side To Side Position And Rear Strap Adjustability Lets You Carry Two Bikes Of Any Size, Type, Design, Color, Creed Or Flavor Right Out Of The Box, Or Carry Up To 4 Bikes With The Optional Plus Two Add On. The Mast Folds Up And Into Itself When Not In Use, And It Also Folds Down For Rear Of Vehicle Access.