Button Definition: "O" long press for 3 seconds : turn the machine on and off+ single press :toggle temperature scale- single press :audible alarm switchBacklight: After 10 minutes of booting, it will be automatically dimmed without operation, and it will be brightened by pressing any buttonAudible alarm value adjustable setting: 10-500PPMSpecificationsProduct Model :PTH-9DCO Range :0~500 PPMCO Accuracy :5% or +10 PPMCO Resolution :1 PPMCO Default Alarm Value :150 PPMCustomize Sound Alarm Value For CO YESCO Response Time: Less than 60 secondsTemperature Range 0 ~ 5 /32~122FTemperature Accuracy:1.5C/2.7 FTemperature Resolution:1C /1FHumidity Range:20%~80% RHHumidity Accuracy:5%Humidity Resolution:1%Battery Spec:LIB -2400 mAhCharge lnput:Type-C Port, 5V/1AProduct Size:98mm x 90mm x 40mmMaterial: plasticcolour: blackPackage Contents:1 x PTH-9D1 x English Instruction manual1 x USB cableOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.