UTK-H10010M 21*31 inches 1.More Effective, Safe, Comfortable, Longer-lasting, Deeper penetrating therapeutic heat for soothing relief of back/lower back/neck/shoulder pain, muscles relax, arthritis, sciatica, NO EMF. 2.More solid construction, secure and sturdy (the pad, connections, controller and the cords); flexible pad can wrap around a body part. 3.The controls are nice and easy to read in a darkened room.