Ametek Crystal 4500 MP Connection Fittings Male to 1/2 NPT Female. CPF is an improved cone type fitting system that adds a unique o-ring sealing system which permits leak free connections without tools. CPF fittings can be directly connected to 1/2" medium pressure cone type fittings from other manufacturers*, provided that wrenches are used to complete the connection.  The fittings of the CPF system have been designed and tested to comply with ASME B31.3-2008, Chapter IX: High Pressure Piping.