Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number DD-4690 REF NO. 16 found under O Ring by Cunico Corporation. The National Stock Number assigned to this part is 5331001675137, 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 DD-4690 REF NO. 16.