Compact Fluorescent UVB Bulbs are an inexpensive way to provide your pet reptiles or amphibians with both UVA and UVB, which greatly improve the well being and health of captive animals. The spiral shape of the bulb enables vertical or horizontal mounting without compromising performance. In general, the higher the number associated with the bulb, the higher the UVB output. Change Compact Fluorescent UVB Bulbs every 6 months. Josh's Frogs carries all the major brands, including ZooMed, Exo Terra, and Zilla!