Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number T520-23 found under Spring Pilot Valve by Spx Corporation. The National Stock Number assigned to this part is 5360004462566, and the Federal Supply Class is 5360 Coil Flat Leaf And Wire Springs. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like T520-23.