ALIEN GardenTank 30A sturdy aluminum frame supports a tough silver PVC membrane to contain up to 30 gallons 120L of water or nutrients, but is collapsible for easy storage when not in use. The heat reflective Mylar lid is secured with Velcro for easy access while dramatically reducing the amount of heat transferred to your nutrient solution. Entry and exit holes in the lid allow pipes to run in and out, and can be covered by screw on caps if not in use. The " 16mm