This is the fitting you'll need on a 3/8" air hose with 1/4" NPT fittings. Milton M-Type coupler plugs are designed to fit this quick connect. This doesn't leak under pressure and requires no lubrication. Assuming you still have all the fingers on one hand, this is easy to operate; hold the ring back with your thumb and forefinger while gripping the hose with your other three fingers. Slip the plug in or out and let the ring go. A small burst of air is normal. This is another quality, made in USA product from Milton. They are the best.