Button Definition: "O" long press for 3 seconds : turn the machine on and off + single press :toggle temperature scale - single press :audible alarm switch Backlight: After 10 minutes of booting, it will be automatically dimmed without operation, and it will be brightened by pressing any button Audible alarm value adjustable setting: 10-500PPM Specifications Product Model :PTH-9D CO Range :0~500 PPM CO Accuracy :5% or +10 PPM CO Resolution :1 PPM CO Default Alarm Value :150 PPM Customize Sound Alarm Value For CO YES CO Response Time: Less than 60 seconds Temperature Range 0 ~ 5 /32~122F Temperature Accuracy:1.5C/2.7 F Temperature Resolution:1C /1F Humidity Range:20%~80% RH Humidity Accuracy:5% Humidity Resolution:1% Battery Spec:LIB -2400 mAh Charge lnput:Type-C Port, 5V/1A Product Size:98mm x 90mm x 40mm Material: plastic colour: black Package Contents: 1 x PTH-9D 1 x English Instruction manual 1 x USB cable Only 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.