Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number ER2001D55 F4 found under Valve Vent by Electric Boat Corporation. The National Stock Number assigned to this part is 4820016642217, 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 ER2001D55 F4.