Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number B4-00-800 PIECE 10 found under O Ring by Rulyn Inc. The National Stock Number assigned to this part is 5331013390718, 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 B4-00-800 PIECE 10.