The Exo Terra Repti-Glo 5.0 Compact Tropical Terrarium Lamp has a moderate to high UVB output, similar to that of shady environments such as rain forests and other tropical locations. Reptiles living in these habitats receive less UV radiation because of the many climatological conditions that prevent direct sunlight from reaching them or their basking sites. The advantage of the Exo Terra Repti-Glo 5.0 Compact Tropical Terrarium Lamp is its size and the fact that it is self-ballasted. A regular screw fitting is sufficient to operate these bulbs. The bulb has wattage of 13, and the spiral shape of the bulb enables vertical or horizontal mounting without compromising performance. Although light is much more complex, there are three facets of light that are important for reptile husbandry: ultraviolet light, visible light and infrared light. In order to create these three biological aspects of sunlight artificially, Exo Terra has developed several specialized lights. Reptiles require appropriate and high quality lighting in order to meet certain different metabolic needs. Fluorescent bulbs lose their UV radiation and approximately 50% of their lighting output quality within one year. Changing your terrarium bulb regularly ensures optimal light conditions and UV radiation to keep your reptiles healthy.