Specification : Color: White Power Supply: One 9V alkaline 6LR61 or carbon zinc battery 6F22 (not included) Sensitivity Setting: CO: sensitivity & time 50ppm: alarms with 60-90 minutes 100ppm: alarms with 10-40 minutes 300ppm: alarms with 3 minutes Smoke: 1%-5%/FT OBS Standby current: <100uA Alarm Current: <75mA Operation Ambient Condition: 5-400C, 20-90% R.H. Method of use: After install batteries, Emit a sound and the red light flash quickly and LED display 888 Pppm mean battery installed correctly, the green flash every 30 seconds to screen out, showed a concentration when the concentration of more than 30 PPM. No show below 30 PPM. Test botton to verify that unit is functioning correctly. One "beep" every seconds is an indication that the battery is low or the unit is malfunctioning. The last alarm value will be record and display when press the button, the green light will flash once eveyr second. Press button again to reset condition. Installation: Select a correct location for your alarm, drill two 5.0mm holes in the ceiling or wall and insert two plastic plugs into the holes, thenattach the bracket to ceiling by using the supplied two screws.Insert and connect a fully charged battery to the alarm.Attach the alarm to the mounting bracket by aligning the locking tab on the bracket to the key holes on the alarm and by twisting the alarm in anti-clockwise. Package includeds : 1 x Carbon Monoxide Detector (Battery not included) 2 x Screw 1 x User Manual Notice: This alarm will only indicate the presence of carbon monoxide gas at the sensor. Carbon monoxide gas may be present at other area. This alarm must be mounted on a wall or a ceiling.