The advantage of a Compact Fluorescent bulb is that it is self-ballasted and fits into most standard screw-in sockets, allowing it to be used in smaller areas. The spiral shape of the bulb enables vertical or horizontal mounting without compromising performance. These bulbs produce both UVA and UVB, which greatly improve the well being and health of captive animals. Bulbs come in 2.0, 5.0, and 10.0 models, with the higher numbers emitting more UV.