The guys at Bezerk RC are a little partial to 12th scale, so when we get the rare opportunity to run on the rug (usually asphalt) we love to try a little spool action. As we run it so rarely, we thought an option would be to convert a regular diff might be a cool idea. So nobody likes square balls in their usual diff, but square balls as a ball replacement might just be what the doctor ordered. So we made a carbon cylinder to replace the balls. Just drop the diff balls out, slip a puck in say every second hole, clean your diff rings and reassemble. Carbon thickness can vary a hint so doublecheck your axle is still centered. Ten pucks come in each set, eight for say a 16hl spur or six in a 12hl works quite fine, so should give you a few spares. Weight for ten of is 0.32 grams. Spur not included!