Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number MC4499 found under Parts Kit Valve by O Rings Inc. The National Stock Number assigned to this part is 1650007871136, and the Federal Supply Class is 1650 Aircraft Hydraulic Vacuum And De-Icing System Components. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like MC4499.