The Heat Index WBGT/HI meter measures air temperature, globe temperature, and humidity to know heat stress index. It is used in control of physical activity in hot environment and limit the danger of heat-related injuries. WBGT Heat Index Meter has a small black ball and can carried easily. It has specific angle, so you don't need to worry about human temperature that might affect the meter’s accuracy. The measurement of WBGT HI Checker can be a good element for monitoring the outdoor activities and prevent people to get heat stroke. It is used in construction, iron and steel foundries, bricks-firing plants, glass facilities, boiler rooms, mining sites, army training, marathon, beach activities and so on. Features Display WBGT, HI, temperature, and RH at the same time for both indoor and outdoor heat stress measurements.Programmable buzzer and red LED warning lights for danger zonesEvery 20 seconds, the display is updated.Size of black ball: 40mm in diameter Environmental Measures Globe TemperatureHeat Stress IndexWet Bulb TemperatureAir Temperature Heat stress meters measure temperature in relation to moisture content and categorize it. The WBGT is the accepted international definition for heat stress (Wet Bulb Globe Temperature Index) Different Heat Control The Heat Stress Index meter integrates elements including air movement, temperature, humidity, and radiant heat to provide the user with an accurate sense of the local temperature. Measurement Range Air Temperature: 0 - 50°C (32-122°F) WBGT Temperature 0-50°C (32 - 122°F) / Alarm range: 20~50°C (68 ~ 122°F) HI Temperature: 0~60°C (32 ~ 140°F) / Alarm range: 20~60°C (68 ~ 140°F) Humidity 0.1-99.9%RH Accuracy Air Temperature: ±0.6°C Humidity 10~90%RH@25°C: Typical 5%, others 7% Accuracy Air Temperature: ±0.6°C / Humidity: 10-90%RH@25°C: Typical 5%, others 7% Set Includes: 1 x WBGT + HI Meter2 x AAA Size batteries1 x Arm Strap2 x BucklesEnglish Instruction ManualStandard Factory Packaging Dangerous Level Indicator CautionWBGT: 26.7~29.4°C (80~84.9°F)HI: 27~31.9°C (80.6~89.4°F)Extreme CautionWBGT: 29.4~31°C (85~87.9°F)HI: 32~40.9°C (89~105.6°F)DangerWBGT: 31~32.2°C (88~89.9°F)HI: 41~53.9°C (105.7~129°F)Extreme DangerWBGT: >32.2°C (>90°F)HI: ≥54°C (>129°F)