The textured, ridged form of the foam Thera-Roll™ penterates deep down into the muscle to decrease pain, soreness and stiffness caused from injury and physical activity. Traditional rollers are smooth and only compress the muscle fibers. The textured design of the TheraRoll™ gives you more control over the roller itself and affects the muscles at a deeper level. The TheraRoll was developed and tested by licensed physical therapists. The level of foam density, firm, was specifically designed for people at the later stages of physical therapy. It is perfect for someone just toward the end of rehabilitating from an injury. This level of density works extremely well for deep muscle relaxation and massage after an intense work out.