DeWitt's Metal Seal HT (High Temp) Ice & Water Underlayment is a self adhering, composite underlayment that is reinforced with an extra heavy fiberglass mat. The polyester fabric surface provides excellent traction, protection from UB radiation, weathering, and oil canning under metal. DeWitt's Metal Seal HT has cold temperature adhesion and exceptional stability under high heat. The self adhesive layer is covered with a high temperature split release film which is removed during installation. It has a 3" wide peel-off top selvage edge to provide additional system sealing at the top laps. DeWitt's Metal Seal HT is 50 mils thick, supplied in two square rolls.