The Exo Terra Solar Glo is a selfballasted mercury vapor reptile bulb that provides the benefits of natural sunlight, which is one of the most important aspects in keeping reptiles healthy. The Exo Terra Solar Glo is the choice of professional breeders as it provides the proper balance of ultraviolet light (including UVA and UVB), visual light and infrared light (heat), in one easy-to-install bulb. The Exo Terra. Solar Glo is a full spectrum light with carefully tuned peaks to ensure appetite, activity, brilliant colours, and optimal calcium absorption through Vitamin D3 production.