Rear High Performance Ring and Pinion Gear Set (YG F10.25-513L) by Yukon Gear & Axle®. Yukon Engineers use state-of-the art design & testing processes, backed by 2 in-house quality labs to ensure each item manufactured meets exacting specifications & quality standards. Yukon designed gear tooth surface finish reduces both friction & heat for long races & high torque conditions. They use high grade steel in both the ring & pinion, with fitment designed to OEM specs.