This 29T Mod1 spool transmission allows you to fine tune the teeth of your vehicle Features Strong and durable steel for long-lasting performance under extreme RC conditions - Precision engineered tooth profile for smooth operation - Precision engineered screw holes for the fitting screws on both sides of the coil shaft for extra secure fit - Fits 8mm diameter shaft. 1 x 29T MOD1 Coil Gear (8mm Bore) 1 x M4 x 4mm Set Screw 1 x M4 Screw Pin