Heavy Duty "Underdrive" Bevel Gear Set (43/13) From AxialUse the gears in different combinations front and rear to reduce torque twist in the rear and overdrive the front axle to help pull you through climbs easierFeatures:The heavy duty gear set offers improved gear mesh reducing slop in the drive trainSpiral cut gears offer increased gear tooth contact and run quieterNew gear ratios offer a low gear and high gear rangeHardened steel for increased strength and additional weight in the axleOne set per axle requiredLaser etched markings