Roof-Mount Bicycle Carriers come in two styles. Fork-Mount style carries one bike securely by front fork and rear wheel; front wheel holder included. Upright style carries one bike locked by the frame with both wheels secured. Carrying clamps feature rubber inserts to help protect bike surfaces. Both styles attach to Sport Utility Bars(sold seperately). Each Bike Carrier holds one bike. Upright Style, . Two carriers can be used per vehicle.