Arrowmax all new gear differential set is now available as a "must-have" option part. It is designed as a direct replacement set to the original ball-differential and requires no additional parts or adjustments. The gear differential is super smooth and is maintenance-free which gives great consistency over a long period of time. It makes the car easier to drive and is suitable for all track conditions. The steel hollow shaft is 6.35mm and is made for the majority of the 1/12 pan cars on the market.