This heated mattress pad delivered the most consistent heat and was the most durable in tests conducted by the Hammacher Schlemmer Institute. Reaching its maximum temperature more quickly than all other tested models, The Best Heated Mattress Pad never deviated more than 1.84% throughout the night, unlike lesser pads that took hours to heat up or couldn't maintain a consistent temperature. The pad showed no shrinkage after multiple machine washings, and its pre-formed top and expandable skirt were easiest to fit over even deep mattresses. The quilted 186 thread-count polyester/cotton cover has 9 oz. of fill that makes the heating wires virtually undetectable. Has 10 heat settings and an automatic shut-off after ten hours; King and Queen sizes have dual LCD controls that allow two sleepers to set their own temperature preferences. Plugs into AC. Twin. 75" L x 39" W.