T-Rex Cobra Heat Mats are the most widely used vivarium heaters in the world. As a primary heat source, this heat mat produces the uniform, evenly distributed warmth reptiles and amphibians require by mimicking the gentle heat of the sun. The mat remains at a steady 100 degrees Fahrenheit, emanating warmth to animals sitting on top of the substrate or cage furnishings. For glass or acrylic aquariums.