Griffolyn Vapor Retarder System stops moisture infiltration from causing poor insulation performance, structural damage, and other moisture-related problems. It consists of several high-performance polyethylene or linear low-density polyethylene reinforced with a patented heavy-duty polyester cord grid. Griffolyn vapor retarder’s low permeance helps to prevent costly structural corrosion, staining, mold and mildew growth, and damaged insulation. Reef Industries. 800-231-6074