Foam roller that features hollow core design and patented multi-density foam surface to deliver firm compression on tight muscle, knots, and kinks to help increase muscle flexibility and mobility • Proprietary Distrodensity surface pattern replicates the feeling of a massage therapist’s hands, helping to relieve tight muscles and enhance recovery • Featuring the patented hollow core design, the GRID retains its shape after repeated and frequent use • Wrapped in durable EVA foam, the roller is firmer than traditional foam rollers and easy to wipe clean • Measures 13" x 5.5" and weighs 1.32 lbs.