2-in-1 WBGT + HI Heat Index Checker Wet Bulb Globe Temperature Heat Stress Meter with Dangerous Level Indicator Audible Alarm. 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 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 meter's accuracy. The measurement of 87784 WBGT HI Checker can be a good element for monitoring 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, training, marathon, beach activities and so on. Resolution:0.1/, 0.1%RH Black ball size: 40mm diameter LCD Size: 40 (H) x 39 (W)mm Stabilization time: 15-25min typical Operating condition: 0-50, Less than 80% RH Storage condition: -20-50, Less than 90% RH Dimension: . 70 (H) x 60 (W) x 22(T) mm Battery life: . 300hrs (The product printed words depending on batch, but this does not affect use) Color:As Shown Material:plastic Package Contents: 1 * HI Heat Index Checker Only above package content, other products are not included. Note: Light reflection and different displays may cause color of item in picture a little different from real thing. The measurement allowed error is +/- 1-3cm.