Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 300C 21 found under Drill Twist by Michigan Drill Corp. The National Stock Number assigned to this part is 5133000515750, and the Federal Supply Class is 5133 Drill Bits Counterbores And Countersinks Hand And Machine. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 300C 21.