These units are installed on LP-Gas motor fuel lines, especially lift truck systems, to provide a quick closing coupling in the fuel line.

The M220M goes on the service valve outlet, while the M220F connects to the motor fuel line. Both couplings have an internal check valve that opens by attaching the two units together. When disconnected, spring force and pressure close the checks. A unique spring clip in the M220M Acme washer helps retain the washer when disconnecting from the M220F.