Pair of hi-lift drums, model 5250-54, for doors with up to 54 inches of hi-lift. These have a 1-inch bore, 500-pound capacity per drum, and accept up to 3/16-inch cable. This 54-inch hi-lift range is common on commercial doors and taller residential setups that need a vertical track section before the horizontal run. Cable length formula for these is floor to shaft center plus 66 inches, minus door height. Comes as a left and right drum. Confirm your hi-lift measurement and shaft diameter before ordering since the wrong drums will throw off cable tracking.