The 13" CORE Foam Roller offers myofascial release, relaxing contracted muscles and improving circulation in sore or stiff muscles. The CORE wall inner support wall is 4mm thick, double that of regular hollow core foam rollers, which tend to crack over time under the average body weight. Foam rollers are used for rehab and other exercise routines. Foam rollers are great for stretching, self-massage, body support, and stability exercises. This roller is perfect to help you roll out those stubborn kinks and knots! This roller has different patterns for different muscle groups. A medium density foam roller. Dimensions: 12"L x 5.5"D.