Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number W420 1.25IPS found under Valve Check by The Walworth Company. The National Stock Number assigned to this part is 4820014654678, 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 W420 1.25IPS.