Mesh Winter Cover 25 ft. x 45 ft. made by Gli 4152040 45-2040RE-ESM-4-bx For 20 ft. x 40 ft. swimming pool. When you protect your swimming pool this winter you’ll be mighty glad you did next spring! When combined with a proper winterizing program, The Winter Cover will protect your swimming pool from the wear and tear of freezing winter weather and eliminate costly maintenance and spring cleanup. Keeps swimming pool water clean and free from dirt, leaves and debris. Stops chemical loss through evaporation Prevents algae growth Protects swimming pool from the wear and tear of winter Eliminates costly maintenance and spring cleanup.