Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number S1-25-005-A ITEM 8 found under O Ring by Parmatic Pollution Control. The National Stock Number assigned to this part is 5331012729879, 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 S1-25-005-A ITEM 8.