Install valve. Connect charging hose. Service. That's all there is to it! MAC features uniport: 1 connection for piercing and servicing. Sealed with refrigerant resistant "O" rings. Needle automatically back seats after servicing, leaving line free of restriction. Connect to tubing with 2 socket-head screws. (Hex wrench is included with each valve.) Needle depressor is inserted into head of needle. Wing cap is turned down easily by hand until line is pierced. Wing cap is removed and system may be serviced with any charging hose with built-in depressor. When hose is removed, spring loaded needle back-seats forming a leak proof seal. Needle depressor is discarded and wing cap forms extra precautionary seal.