The RumbleRoller has specially designed bumps that are firm, but flexible. As you roll, the bumps continuously kneed the contours of your body, gently stretching soft tissue in multiple directions. The Rumble Roller targets trigger points, helps restore flexibility, and brings quick relief to common types of muscular pain. Conventional foam rollers have smooth surfaces that compress soft tissue. Rolling on top of them improves blood flow and tissue flexibility, but the effectiveness can be limited unless you spend a lot of time rolling. The RumbleRoller was created for more effective therapy. The firm but flexible bumps of the Rumble Roller are like the thumbs of a massage therapist. The bumps are less than 2 inches apart, so several of them simultaneously contact your body during most exercises. With a slight shift of your body, you can reduce your area of contact with the RumbleRoller, which increases pressure and provides deeper, more penetrating relief. Because the bumps have an asymmetrical shape that allows them to flex more easily in one direction, the massaging action can be increased by changing your movement from a back-and-forth rolling motion to a side-to-side rocking motion. The RumbleRoller is stronger and more tear resistant than conventional foam rollers and it permanently retains its shape. The smooth, nonporous surface is latex free, repels dirt and is water-proof.