To suit 1/10 scale models made by Hi Speed will fit a few other models using a .12 to .18 size engine not all. To help ensure a fit please check measurements below.14T Clutch Housing 20.4mm wide outer diameter 28.1mm.2 x Ball Bearings included 10mm x 5mm x 4mm. Lightweight alloy flywheel Outer diameter 34.93mm - Center hole dia 5mm.Axle to fit 5mm crankshaft thread 21.43mm long entire length.Axle requires not included M3 x 8 metric thread screw and a couple of washers.