The heating element is insulated on the bottom and radiates heat to the top surface. Uses 110-120 AC. Features beveled edges and an extra support rod. Comes in single or double size. Can be installed with or without thermostat-based temperature controls. When installed without temperature controls, mat will heat to a constant temperature of 37?F above ambient temperature.?36 Single size features 64.17 watts, 48 Single size features 84.33 watts, 36 Double size features 128.33 watts, 48 Double size features 168.66 watts.36 size has 18 stainless steel electrical cord protector with a 10' electrical cord.?48 size has 20 (1-1/2 dia) PVC cord protector, 10' cord; comes with 45? elbow and 2 mounting brackets.?48 sizes require a UPS special handling Charge.