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 #16021-413-751, 16021-438-671, & 16021-463-004. 4-piece set. Diaphragm with 54.13mm long rod, spring and rubber boot for rodThis item fits the following models: 1980-1981 Honda CB400T Hawk1982 Honda CB450SC Nighthawk1982 Honda CB450T Hawk1981-1982 Honda CB900F Super Sport1980-1981 Honda CM400T1980-1982 Honda CX500C Custom1980-1981 Honda CX500D Deluxe1982 Honda CX500TC Turbo1980-1983 Honda GL1100 Gold Wing1982-1983 Honda GL1100A Gold Wing Aspencade1980-1983 Honda GL1100I Gold Wing Interstate1981-1982 Honda GL500 Silver Wing1981-1982 Honda GL500I Silver Wing Interstate