Heat therapy relaxes muscles and relieves joint pain and soreness. By increasing blood flow to the injury area, heat therapy can help accelerate healing. Finally, heat can effectively warm and loosen stiff muscles before exercise. Ultra's advanced timed-release moisture technology provides deeper heat penetration than dry heat alone. Moist heat is physician recommended. Optimal heat therapy requires consistent heat in the therapeutic range. Ultra uses state-of-the-art microchip technology to eliminate spikes and maintain a more comfortable, even heat. Ultra also has a bonus "warmth" setting for subtle, gentle warmth.