1Mute button: Turn on or off the alarm sound. In the silent mode, the "volume prohibited" sign is not displayed and there is no alarm sound. The default is to turn on the sound. 2"+" button: when setting the alarm value, increase the value; power button: press and hold for 2 seconds to turn on or off the power, when the power is turned on, the number field will count down from 120. 3Air quality detector temperature unit selection button: conversion between Celsius and Fahrenheit. 4Setting button: short press this button to set the alarm value of "CO2TVOCHCHO" in turn, display the original factory setting value and flash. 5Use the "+" button and the "-" button to adjust the parameter, the value will be automatically stored after 10 seconds. Item Type: Air Quality Monitor Material: ABS Model: JD-3002 Alarm Sound: Press "mute button" to operate. CO2 Measurement Range: 350ppm2000ppm TVOC Measuring Range: 0.000 mg/m2.000 mg/m HCHO Measuring Range: 0.000 mg/m1.000 mg/m Temperature Display: Press "temperature unit selection button" to operate Measuring Range: 090.0(accurate 0.1) 32194(accurate 0.1, above100display integers) Environmental Quality Tips:Excellent: The detection value is lower than the set value Good: CO2 detection value is 50ppm higher than the set value The TVOC detection value is 0.01 mg/m higher than the set value HCHO detection value is 0.03 mg/m higher than the set value Pollution: Rapid sound alarm by buzzer CO2 detection value is 100ppm higher than the set value The TVOC detection value is 0.02 mg/m higher than the set value HCHO detection value is 0.06 mg/m higher than the set value When the battery power is too low, the battery box will flash to remind the user to charge When charging, the characters in the battery frame will flash sequentially until the battery character is completely displayed when the battery is completely charged Humidity Display:Measuring Range: (099.0) %RH (Precision 0.1) Power Supply: Built-in 3.7V lithium battery 2000mah 1 xDetector 1 xCharging Cable