Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 20A11BM251 found under O Ring by Curtiss Wright Electro Mechanical Corporation Dba Steam And Air Solutions Div Cu. The National Stock Number assigned to this part is 5331010050545, and the Federal Supply Class is . Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 20A11BM251.