... (National Pipe Thread); Shape: Female, male, hose barb, plug, nipple, push on hose barb; Material: Brass or steel; Thread size: 1 ... ", 3/8", 1/2"; Coupler type: ARO type, A type, push type; Surface treatment: Zinc plated; Working pressure: No more than ... working pressure, air leakage, surface finishing and thread test. Air Fitting(Air Coupler, Pneumatic Coupling)