The JR Super Speed Gear Set Super X & Super-II produced by Tamiya, is classified in Mini 4WD / Kids - Mini 4WD Spare Parts - Gear Specs and Features Gear Ratio = 3.5:1 2 types of shafts are included to enable installation on more types of Mini 4WD chassis. Compatible with Super X, Super XX, Super-II, Super TZ, Super TZ-X, AR, FMA, VZ and VS chassis machines.