This axle starts life as an official B.S.A. Pinewood Derby axle. It is C.N.C. machined true and round, we then add 2 grooves (1 large main groove and 1 small groove behind the axle head) to reduce friction and hold graphite then head is back-cut for further friction reduction at the hub face on the wheel. They are semi-polished so the builder can finish it their spec.