Each set contains 1 diaphragm with rod attached, 1 rubber boot for rod, spring and O-ring as required. Sold as a set, 3 or 4 piece as noted. Replacement OEM #16021-679-005. 3-piece set. Diaphragm with 54.01mm long rod, spring and rubber boot for rodThis item fits the following models: 1980-1982 Honda CB750C Custom1979-1982 Honda CB750F Super Sport1979-1982 Honda CB750K1979 Honda CB750L1982-1983 Honda CB750SC Nighthawk1980-1982 Honda CB900C Custom