Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 55128 found under Guide Valve Disk by Tyco Valves And Controls Lp. The National Stock Number assigned to this part is 4820008629409, and the Federal Supply Class is 4820 Valves Nonpowered. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 55128.