The Solarmeter Model 6.5 allows for instantaneous, highly-accurate readings of the UV index. This professional instrument (NIST traceable) is ideal for the study of meteorology (solar intensity). The UV index is often reported in weather forecasts as a way to determine the likelihood of sunburn. Any reading over 3 indicates the need for some protection – 8 and higher is extreme! This device is also great for monitoring all types of UV sources for intensity and aging (helpful for the care of animals requiring UV such as reptiles). Uses one 9-volt battery (included).