Twin, Heated Mattress Pad By Electrowarmth, Size 38 X 74, Model# M38f polyester Ultimate Sleeping Comfort-You sleep on it NOT under it ! - Save energy by turning your house thermostat down. The Electric Bed Warming Pad goes on the mattress and gives soothing warmth comes from underneath Made from two sheets of fine weave, pre-shrunk poly/cotton cloth quilted together, similar to a high quality mattress pad. The closely quilted seams form tunnels, and hold the heating element wire inside for uniform heat distribution. All models are padded with bonded polyester fill, similar to a mattress pad. Twin Size 39x74, MADE IN USA