Serta Sherpa Top Low-Voltage Electric Heated Mattress Pad- stay comfy with the all over penetrating warmth of this low-voltage mattress pad. The incredibly luxurious 100-percent polyester 180gsm Plush Sherpa Fabric not only warms your bed, but also rejuvenates it. Constructed within the pad is the patented Safe and Warm low-voltage technology. This low-voltage mattress pad includes a small power supply box that changes 120 volt AC home current into non-hazardous low voltage DC current (very similar to a battery) to provide warmth, protection and safety even if the pad becomes wet. Unlike other warming pads with their thick bulky wires, the wires in the Serta pads are so small and thin; they are virtually unnoticeable. During construction we place the thin wires 3-Inch apart and evenly distribute them from head to toe to give even heat and eliminate annoying hot or cold spots. The queen size pad is divided in two separate zones and comes standard with two easy to read, easy to turn, non-slip computerized controllers to individually adjust the temperature of each side of the bed. A giant backlit display with auto dimming feature provides more convenience for night time adjustments without having to turn on the lights. For cozy sheets before bed time, it has an automatic pre-heat and hold feature. You simply turn it on and the pad will warm up on HI until it reaches the temperature that you pre set your dial on and then adjusts itself to hold it there. For your safety, convenience and power conservation it has an automatic shut off feature that will shut the pad off after 10 hours just in case you forget. It also comes standard with built in over-temperature protection for that extra bit of safety and peace of mind. A fitted skirt keeps it all in place to eliminate shifting or bunching and gives better sheet fit. Conveniently machine washable and dryable. Not recommended for use with an electric adjustable bed, water bed or blowup air beds (Sleep Number beds are OK).