This aluminum screw on gas cap fits old style “Coffin” and “Peanut” gas tanks. It uses an O-ring as a seal. It comes with 3 feet of Tygon tubing.These fit 1962 to 1969 thread on gas tanks. The thread is 45 mm x 1.5 mm. They do not fit the 1/4 turn tanks or the newer coarse thread gas tanks.