Ametek Crystal 4698 MP Connection Fittings Male to 1/4 NPT male. Non-Crystal MP adapters (wrench tight), fittings rated to 15,000 psi, male-to-male and male-to-female. The Crystal 4698 MP Male to 1/4 (0.25") NPT Male CPF Fitting is an improved cone type fitting system that adds a unique O-ring sealing system which permits leak-free connections without tools. The fittings of the CPF system have been designed and tested to comply with ASME B31.3-2008, Chapter IX: High Pressure Piping.