Preassembled SafeScreen Aquarium Mesh Screen Lid We've Got You Covered Provide protection for your livestock and encase any aquarium with this mesh screen lid cover. Glass lids trap in heat, do not allow proper evaporation and build up salt creep that can impeded light penetration. This stylish mesh screen top is the answer to these woes by being lightweight, allow zero heat buildup, and have very little impact on light penetration. The outside rail edges have been molded with a lip that allows your lid to sit neatly on the inside edge of your aquarium. No need for clips or screen holders.