Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number K520-4C-PC found under Switch Push by American Zettler Inc. The National Stock Number assigned to this part is 5930011590714, and the Federal Supply Class is 5930 Switches. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like K520-4C-PC.