A tough-faced superior self-adhering, air/vapor barrier and waterproofing membrane for vertical and horizontal above grade substrates; BT25XL seals window perimeters to building substrates to create an impenetrable barrier. This 25-mil polyethylene-backed aggressive rubberized adhesive membrane can be applied to vinyl, plywood, OSB, concrete, metal, aluminum, polyethylene, building wrap products, block and masonry surfaces to form an air/vapor moisture barrier system. BT25XL is the only window sealing tape that can be installed and left exposed for 120 days without UV degradation. Since BT25XL is a peel and stick self-adhering membrane, you simply center the tape over the area to be sealed and firmly roll and press into place. BT25XL also seals itself around nails, screws and staples. Not only will BT25XL waterproof around doors and windows, it stops air leakage, thus reducing heating and cooling costs.