The advantage of the Exo Terra Repti Glo Compact Fluorescent bulb is its size and the fact that it is self-ballasted. A regular screw fitting is sufficient to operate these bulbs. The spiral shape of the bulb enables vertical or horizontal mounting without compromising performance.It is recommended to combine a high UVB output (Repti Glo 5.0 and 10.0) with a very high visual light output (Repti Glo 2.0) for optimal results. Fluorescent bulbs do not provide sufficient heat. A separate heat source is required in addition. The Exo Terra Repti Glo 10.0 has a very high UVB output similar to that associated with desert environments. Desert locations receive more direct sunlight than any other because of fewer clouds less air humidity and no plants or trees to provide shade. Therefore desert reptiles are more exposed to UV radiation than any other type of reptile. This bulb can also be used on screened terrariums or terrariums with dense screen covers to ensure UVB penetration. Dense screens can filter out up to 50% of the UVB rays. - Ideal for all desert dwelling reptiles. - Ultra High UVB output. - Effective up to 50 cm (20\"). - Provides necessary UVB rays for optimal calcium metabolism. - Recommended for use with screened terrariums; terrariums with dense screen covers (screens can filter out UVB rays). - Recommended in combination with Repti Glo 2.0 for a higher visual light output.