Standard terrarium bulbs can't deliver the heightened levels of UVB radiation native to a tropical habitat, leaving rainforest reptiles deficient in a vital component of healthy bone development. Tropical 25 Bulbs correct this deficiency with a full dosage of UVB (25 microwatts per second/cm2) along with essential UVA light. As a bonus, Tropical 25's full-spectrum visible light output helps bring out subtle colors in a reptile's skin that makes everyday viewing more dramatic. Tropical 25 capability is built into R-Zilla's complete family of high efficiency bulbs for most types of fluorescent fixtures. Tropical 25 bulbs are designed for 3500 hours or twelve full months of average use.