►   Quickly and easily monitor your exposure to ultraviolet radiation from the sun
►   Measures both UV-A and potentially harmful UV-B radiation
►   Date, time and alarm functions to help you monitor your UV radiation exposure
►   UV index measurement from 0-20 (in 0.5 increments)

Ulta Violet light is typically found as part of the radiation received by the Earth from the Sun. Most people are aware of the effects of UV radiation through the painful condition of sunburn on the skin. The UV spectrum has many other effects  some are beneficial to human health and some are damaging. 

Many people keeping reptiles, lizards, tortoises want to make sure creatures are getting the right amounts of UV radiation so that there welfare is maintained at a high level.  see http://www.uvguide.co.uk/whatreptilesneed.htm