Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 257-280A found under Valve Regulating Fl by National Torch Tip Co Inc. The National Stock Number assigned to this part is 4820011355064, 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 257-280A.