Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number AB20S found under Valve Air Bleed by Deltrol Corp. The National Stock Number assigned to this part is 4820012001888, 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 AB20S.