We've designed an electric mattress pad that not only warms your bed, but also protects and rejuvenates it. The waterproof 233-thread count 80-percent poly/20-percent cotton dobby stripe decorative shell is incredibly soft and soothing. A special TPU Laminate waterproof barrier and Stain Repellent Scotchgard Finish protects against spills and accidents of all types, but that's just a couple of the wonderful features of this pad. 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. The benefit to you is a pad that gives more of an even heat and has no annoying hot or cold spots. The king size pad is divided in two separate zones and comes standard with two easy to read, easy to turn, non-slip computerized controllers to adjust the temperature of each side of the bed giving individual comfort and control. A giant backlit display with auto dimming feature provides more convenience for night time adjustments with out 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-hour 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.