This is a Parkair CP21 pneumatic quick release coupling, couplings and nipples are manufactured from nickel plated brass. These couplings are design to interchange with the Rectus 21KA Couplings. This range has a maximum working pressure of 35 bar with a flow capacity of 560 l/min. This coupling is valved which is closed when disconnected.
Nominal flow diameter is 5mm (3/16")
Flow Capacity is 560 l/min (19.4 CFM) measured at 6 bar (87 psi) with a 0.5 bar (7 psi) pressure drop
Max working pressure 35 bar (507 psi)
Temperature range -20°C to +100°C (-4°F to +212°F)
The Parkair CP21 Quick Connect Couplings is evocative, to say the least, but that's why you're drawn to it in the first place.