mfm Building Products - Flex-Clad-400™ is a pre-fabricated, self-adhering, sheet-type protective membrane. The outer layer is an embossed, UV-resistant aluminum weathering surface. Under the aluminum are multiple layers of tough, high-density cross-linked polymer film. Under the polymer film is a uniform layer of aggressive rubberized asphalt adhesive which sticks directly to metal, insulation facers and most other clean, dry surfaces. The self-adhesive surface is protected by a disposable release liner.