Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number M1904B found under Ring Piston by Twin Disc Incorporated. The National Stock Number assigned to this part is 4310001166763, 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 M1904B.