This is an optional Yokomo Steel Bevel Differential Gear Set. This gear set is compatible with the B-MAX2 MR ver.2, B-MAX2 MR and RS 1/10 buggies equipped with the optional Gear Differential (YOK-B2-500GS). These gears are more durable than the stock composite gears and are recommended for high traction conditions when the differential is subjected to high loads.