Automatic Rebound roller wheel Desig Our ab roller adopts automatic rebound technology, which helps protect muscles from stress during exercise. Moreover, the auto-rebound feature helps beginners tighten their core, standardize movement, and keep exercising for longer periods of time. The built-in smart braking system makes the rebound smoother and protects the user from injury. Wheel Desig Different from single or thin wheel Ab wheels on the market, this elbow support abdominal wheel has 105MM wide front and rear wheels for smooth rolling and better control. It can help you exercise every muscle and core while controlling your body more safely, especially for beginners. Wear-resistant material The roller is wrapped with soft material, which has good sound insulation effect. It is safer to use and won't hurt the floor.