Zilla T8 Fluorescent Bulbs provide UVB light rays which are required for many reptiles to metabolize essential calcium. Recommended for use with Zilla T8 Strip Light Fixture. Zilla Tropical 25 Bulbs provide a full dosage of UVB (25 micro-watts per. second/cm2) along with essential UVA light. Zilla Desert 50 Bulbs provide a full dosage of UVB (50 micro-watts per. second/cm2) along with essential UVA light. Replace every 12 months to ensure proper UVB levels. Zilla is committed to producing innovative products to build and maintain a healthy reptile habitat. From terrariums for your bearded dragon lizard to bark bedding for your frog, and floating turtle platforms, we provide what is necessary to get a terrarium or vivarium started. Essentials such as reptile food, humidity & temperature gauges, heat, light, accessories, and supplements are also available from Zilla products. We make it easy for you to get your first pet reptile, to grow in the hobby, and to become an enthusiast. For those seasoned reptile keepers, we are committed to innovation.