Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 15990 found under Valve Linear Directional Control by E Systems Inc. The National Stock Number assigned to this part is 4820005872429, 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 15990.