The YCS 120 MIL Vapor Barrier is constructed of a white woven top, closed cell foam core, and metallic film backing. While the woven top could stand alone in just about any crawl space project, the foam and metallic film backing provide a thermal break when installed vertically on walls. The reflective side helps control radiant heat loss/gain in addition to added thermal protection. The 120 MIL also carries a 0.00 perm and has a high-tech film on the topside that resists soil gasses like radon. The 120 MIL will provide the ultimate finished look in crawlspace/basement projects. As a ground liner it pairs well with the YCS Seam Weld. As a wall liner, it pairs well with Magic Adhesive and Wall Attachment Tape.