The image beside is the simple chart to give you he basic 8 cam and groove fittings.
Part numbers that start with the letter ( G ) are the Global import line ( normally cheaper )
Part numbers starting with just a number are going to be
domestic non-imported parts
The two letters at the end of the part number are
below to explain abbreviation.
AL = aluminium
SS = stainless steel
MI = malleable steel
example --- G400-D-MI
G = global, 400 = 4", D = FNPT x F cam, MI = malleable iron