Bendix Straight 1/2" Single Check Valve 

1/2 Inch NPT Female Inlet 1/2 Inch NPT Male Outlet

Part Number:   5003980 

                         5003524

NSN Number:   4820-01-549-7410

                           5331-01-160-9852

General Dynamics Part Number:   10628245-2 

Volvo Number:        7455003980

New Flyer, Gillig, Mohawk Part Number:  5923496