Just presses power button, keep the device turned on and it will take the measurement automatically. The lithiums battery provide power, standbys time can last for 6hours (supplied with USB cable and Benefits from the alarms including a buzzers and for immediate pollution warnings, complemented by function Equipped with a fast-responding and sensitive highs chip, the air monitor can precisely the weak current during electrochemical reactions. color & voice alerts keep you inform of current air conveniently With its small size designs and a rechargeable battery, making comprehensive air monitor accessible his indoor air monitor accurately assesses intemperature & humidity and formaldehyde (HCHO), It is necessary to know the air where you live , can help you understand indoor air, Manufacturer: REITINGE