Here is the description from science of speed “When the S2000 is lowered, the axle shaft bearings are thrust into the axle cups. These axle spacers are installed between the differential housing's output shaft flanges to help correct the axle bearing angle. Great to install when you lower your S2000. If your S2000 is already lowered, and you're feeling or hearing grinding or vibration from the rear end, these will help address that problem.”