In The Swim 18 ft. Round Micro Mesh Pool Winter Cover Micro mesh pool cover traps the finest silt and debris preventing them from contaminating your pool Hems are stitched with heavy-duty U.V. treated polypropylene thread to resist rot Has a black underside to inhibit algae growth All pool covers come complete with heavy-duty vinyl coated cable and winch Has reflective silver coating on the top to speed up the snow's melting process