GLI Pool Products ProMesh 20-1840RE-PRM-GRY-AC 18' x 40' Gray Rectangle Safety Cover. This state-of-the-art cover material provides solid coverage benefits without any added weight. ProMesh covers come standard with stronger-than commercial grade springs on all custom covers which provides tighter, stronger security for your pool. If you open your pool in mid-spring and are looking for the benefits of a solid safety cover without the weight associated with it - this is the cover for you!