Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 5500A4003 found under Pneumatic Muffler Exhaust Intake by Ross Operating Valve Co. The National Stock Number assigned to this part is 4310016088993, and the Federal Supply Class is 4310 Compressors And Vacuum Pumps. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 5500A4003.