attwood Pontoon Boat Covers (17-Feet - 20-Feet) Snug Harbor covers are made from 100 percent polyester With any trailering cover it is most important to prevent wind bagging Tie-down loops above the gunwale help keep the cover down while allowing the elastic hem to be pulled tight against tapered hulls Snug harbor covers have 1/2 inch poly webbing sewn across each cross seam to strengthen the cover for towing Quality features and strong polyester fabric allow us to offer a 3-year warranty This fabric is strong, color fast, and waterproof great for trailering and outdoor durability Webbing also provides a stronger attachment point for the gunwale tie-down loops Snug harbor covers include an adjustable elastic cord that runs the full length of the hem Outstanding tear strength, burst strength and abrasion resistance