The Solarmeter Model 6.2R uvb meter includes a silicon Carbide (sic) photodiode packaged in hermetically sealed UV glass window cap. Interference filter blocks most UVA from response as shown on Spectral sensitivity graph. This meter is specifically designed to monitor reptile lamp intensity and aging. To operate, press and hold push-button switch on face of unit. Aim sensor window in top panel of meter directly at UV source. Note reading on LCD and record If desired. Battery operation voltage is 9V down to 6.5V. Below 6.5V the LCD numbers will begin to dim, indicating the need for battery replacement. Under typical service load, the battery should last approximately 2 years.