This Robelle Premier Supreme Plus rectangular solid winter pool cover features a 12 x 12 Scrim count (threads per square inch) and a material weight density of 3.7 ounces per square yard. The Slate Blue topside has been treated to inhibit damaging ultraviolet rays. A black underside prevents the growth of algae. Made of polyethylene, this exceptional quality in-ground winter pool cover has a 5-ft overlap, allowing the cover to be secured with water tubes on the pool deck. There are grommets located on each of the four corners of this cover. The overall size is 25'W x 45'L. It is designed for a rectangular in-ground pool. All Robelle Supreme Plus winter pool covers come with a 18-year warranty. Water Bag loops approximately every 4 feet.