Silicone coated ripstop nylon. Unlike other silnylon fabrics on the market, our silnylon is made specifically to be both windproof AND waterproof. These fabrics are coated with a silicone layer on each side and are non-breathable. Great for projects such as trail tarps, tents, stuff sacks, backpacks, kites, or any gear/project where waterproof/windproof fabric is needed.