The part a adapter is the male adapter x female NPT half of a cam and groove pair. In 2-1/2" and brass, it covers most of what a transfer line asks for.
Size: 2-1/2"
Type: Part A adapter
Connection: male adapter x female NPT
Material: brass
Maximum allowable working pressure: 150 psi
Pressure rating is based on Buna-N seals below 100°F
Cast, machined and assembled in the USA
Assembled with solid pins
Complies with Commercial Item Description A-A-59326D for quick disconnect couplings
Not rated for compressed gas service, including air and steam