Large cooling fans provide powerful ventilation to reduce heat transference from aquarium equipment. Extremely quiet operation with adjustable positioning, perfect for saltwater aquarium (Reef & Frag tank) and fresh water aquarium. Generates 10 times more cooling power than conventional fans to reduce temperature buildup by 5 to 7 degrees Fahrenheit. Easy to install - no tools needed. High-quality plastic construction. 12V UL-Listed. Powerful cooling fans increase air movement to reduce heat and humidity. Minimizes unwanted water temperature increase due to aquarium equipment. Extend Longevity of your lighting system. Note: Clamp mounting bracket can fit over aquarium walls up to 1/2" thick. Please make sure the thickness of your aquarium wall (or the width of the lip around the top edge of your aquarium) is less than 1/2 inch. These cooling fans are designed primarily to fit over salt water aquariums made with fortified glass, which are typically rimless (no lip). But we can offer a quick fix for this problem. We suggest that you purchase a piece of clear plastic (or pixie glass, they usually come in pre-cut 8×11 pieces) and a tube of epoxy (a special plastic adhesive). Glue the clear plastic piece to the outside of the edge. The plastic wall should rise at least 1 inch above the edge of your aquarium; this will ensure a secure fixture of the fan to the plastic wall. Ventilation Tips: Use cooling fans during summer, in warm areas with little or no air movement, or in areas with equipment that generates excess heat. Maximize air movement in an enclosed area with two cooling fans instead of one unit. Place one unit on one end to introduce cool, fresh air and the other unit on the opposite end to exhaust the warm air. The cross-ventilation will efficiently reduce heat generated by aquarium equipment.If placing cooling fan in cabinet, the cabinet MUST have an open back for proper ventilation.