Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number A-591 found under Seat Valve by Curtiss Wright Electro Mechanical Corporation Dba Steam And Air Solutions Div Cu. The National Stock Number assigned to this part is 4820005646805, and the Federal Supply Class is 4820 Valves Nonpowered. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like A-591.