2 Models avalable; both models have dual sealed ball bearings having double row balls and drum brake included. Kit comes with choice of 44T, 48T or 56T chain wheel sprocket Model 1: with freewheel for attaching chain sprocket; this model is used for pull start engines; can be used for 2-cycle or 4-cycle non pedal start engine applications Model 2: made for pedal start engine applications where a solid flange hub is required for sprocket attach; other wise same as model 1