The HT30 Wet Bulb Globe Temperature (WBGT) meter allows you to measure Heat Stress Index, or how hot it feels when humidity is combined with temperature, air movement, and radiant heat. The meter can also take individual temperature, humidity, and radiant heat measurements as well as monitor the effects of direct solar radiation on an exposed surface using the Black Globe temperature sensor. An in/out function displays the WGBT value with or without direct sun exposure. Additional features include Auto Power Off with override and a built-in RS-232 interface. Complete with 2 AAA batteries.