Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number C5603 found under Ring Piston by Hydro Line Mfg Co. The National Stock Number assigned to this part is 4310004670967, 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 C5603.