Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number N491200057 found under Seat Valve by Leslie Controls Inc. The National Stock Number assigned to this part is 4820000750373, 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 N491200057.