This is designed to fit a variety of boat lengths, cut into general catamaran shape. It’s made of tough woven polyethylene that is coated on both sides, one side silver, one side black. Hobie ahs chosen this polyethylene because of its excellent resistance to ultra-violet degradation. It is a woven rather than sheet fabric to provide great tear strength. These covers will tolerate sun, wind, rain, high and low temperatures, and not fall apart. This fabric was specially designed for outdoor application. Install with silver side out. Each cover is cut to be used for a boat length range. Tapes are sewn in place to allow you to secure the cover around the hulls and crossbars. Custom features such as cut outs or slits for wires or wings can be created with scissors. The edges will not catch, fray, or pull. We include 5 feet of adhesive backed velcro with each kit to be used to prevent slits from flapping in the breeze. For the 17' to 18' range.