This product is carbon monoxide detector. It’s the only battery-operated alarm that includes a backlight digital display feature. The backlit digital display feature allows for easy viewing of carbon monoxide levels from 001-999 PPM (parts per million).When concentration of the leaked carbon monoxide reaches the given alarm level, the detector LED flashes red and buzzer gives out alarm sounds. This product can be well used in villas, factories, shopping malls, warehouses, office buildings etc. indoor places.