Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 5399 005R 1 1 2IN ITEM 12 found under O Ring by Milwaukee Valve Company Inc. The National Stock Number assigned to this part is 5331001675124, 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 5399 005R 1 1 2IN ITEM 12.