Zilla Desert 50 UVB Fluorescent T8 BulbWhen it comes to the bone health of a desert reptile, the extra daily dose of UVB light provided by a Zilla Desert 50 bulb (50 microwatts per second/cm2) is as essential as proper food and water for long term strength. The Desert 50 family of bulbs also provide needed UVA light, plus visible-spectrum illumination that makes skin coloration more vivid and viewable. Get all this in a family of high-efficiency bulbs designed to fit most major fluorescent fixture types (compact, T5 and T8). Desert 50 bulbs are designed for 3500 hours or twelve full months of average use. Bulb length is measured from end of pin to end of pin.