Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 277863 found under Valve Linear Directional Control by Mk Test Systems. The National Stock Number assigned to this part is 4820008517674, 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 277863.