Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number FI21.72AGB 350MM PN12 found under O Ring by Naf Ab. The National Stock Number assigned to this part is 5331014262558, 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 FI21.72AGB 350MM PN12.