Crumb Rubber has the ideal durometer rating to absorb bounce and shock, preventing damage to your olympic lifting bar. Crumb Rubber technology dissipates the impact giving you 10,000 – 30,000 drops and reducing stress on the lifting bars. On the field tests have shown XM Crumb Rubber Bumpers bounce less than other high-end rubber bumper plates on the market. Less bounce equals less shock and less noise.