GLI Pool Products HyperLite 20-1840RE-HYP-BLU-P-AC 18' x 40' Blue Rectangle Safety Cover. Another staple in our stellar collection, this arm of our solid cover options are not only secure, but they are also 30% lighter than standard solid covers and each comes standard with our distinctive Commercial Grade Springs on Custom Covers. Contains improved strength and puncture resistance - the ultimate in durability, which is able to withstand puncturing from falling tree branches, deer hooves & the claws (etc.) from other animals. Provides 100% Sunlight Blockage, which means there will be NO spring time algae growth in your pool.