8121M0500104MZ is an industrial-grade, self-venting fuel cap manufactured by Stantel. It is a push-in style fuel cap designed to fit a variety of threaded tank openings. The cap is made of metal and features a metallic outer covering which helps to protect against impact and wear. It comes with a 3 bar (45 psi) vacuum relief valve and a tamper-proof seal which prevents unauthorized access to the fuel tank. This product also meets California Environmental Protection Agency TUV/CDPH requirements for vapor recapture systems.