Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 957-00066 found under Disk Valve by Permutit Co The. The National Stock Number assigned to this part is 4820012090467, 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 957-00066.