Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 521 327-428 found under Switch Rotary by Butler Newall Inc. The National Stock Number assigned to this part is 5930013182236, 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 521 327-428.