Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number A2-503-16 found under Valve Angle by Marshall Engineered Products Co. The National Stock Number assigned to this part is 4820003162659, 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 A2-503-16.