Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number S2-99 found under Filter Element by Industrial Filter Mfrs Inc. The National Stock Number assigned to this part is 3655007335657, and the Federal Supply Class is 3655 Gas Generating And Dispensing Systems Fixed Or Mobile. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like S2-99.