Heavy Duty 10 mil made in USA. Polyken Duct Tapes - Duct tapes offer triple-layer construction consisting of a polyethylene plastic backing for waterproofing, a cloth middle layer that provides strength and affords a straight tear and a rubber-based adhesive for durable holding power. Multi-purpose tapes have a higher thread count for greater strength, a thicker PE backing for increased durability and more adhesive for better holding power. Premium-grade tapes are constructed for long-term, demanding applications. They often contain additives or special formulations, which provide resistance to sunlight and harsh conditions.