Pinewood Pro Derby Car Machined PRO Polished Speed Axles, Nickel-Plated with 2 Grooves and angled head minimizes friction to get the fastest axle (4 axles) PRO SUPER SPEED machined axles, perfectly straight pinewood derby axles designed for SPEED NICKEL PLATED with a mirror finish makes the fastest derby car axles GROOVED AXLES 2 grooves reduces friction and wheel wobble with secret graphite store for a super fast axle ANGLED HEAD  reduced friction when wheel touches head OVER SIZED SHAFT  at 0.91" for a tighter fit in the wheel bore reduces wheel wobble