This lightweight rear brake rotor is laser cut and precision ground from high quality 410 Stainless Steel and is more than a pound lighter than the OEM rear brake rotor. The OEM rotor weighs 1 lb. 12.9 oz. and this modified rotor weighs only 11.2 oz! This is for closed course race use only. Yes, if you were wondering, this will actually still stop the bike just fine with the rear brake. Improving handling, acceleration, and braking by removing unsprung rotating mass from your motorcycle.