Stratasorb Waterproof Adhesive Island Wound Dressings boasts four layers of protection and convenience! Layer 1 is an innovative non-adherent contact layer, while Layer 4 is a semiocclusive, waterproof polyurethane film - yielding unparalleled protection against external contaminants and maintaining an optimum wound environment. Plus, a nonwoven backing with an adhesive border keeps the dressing in place, making it an ideal primary or secondary choice.