Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number M3900-8SB found under Switch Rotary by Cole Instrument Corp. The National Stock Number assigned to this part is 5930013538649, 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 M3900-8SB.