Gladhand Coupling, ROYAL BRASS AIR BRAKE GLADHAND COUPLING

It's got a 1/2 inch female pipe thread, so it should fit standard connections.

Half-inch female pipe thread is built right into it, so if your air brake line terminates with a half-inch male pipe fitting, you're connecting directly without any adapter in between. It also conforms to SAE J318, which is the standard most commercial and industrial air brake systems are built around, so fitment on compliant setups is straightforward.