This is an optional Robinson Racing Axial Yeti Gen 3 Slipper Unit with Blackened Steel Spur Gear. GEN3 Slipper Units will not fail under the enormous load conditions of todays brushless motor systems. The GEN3 Slipper Unit is a captured design to prevent slipper pad blowout and deliver maximum power to the ground. The hi-performance hardened steel spur gear will not fail or strip. Strong and tough gear teeth handle all the power you can pour on the spur gear. Aircraft grade billet aluminum backplate will not bend or break. Increased surface area of the oversized pad insures dependable performance. Less total parts reduces flex and wobble in the spur gear and slipper unit. Choose from 56 or 64 tooth spur gears. Bearing, Steel Spur, Slipper Pad and Backplate included.