Features: 1) Electrochemical or semiconductor CO sensor with industrial grade 2) Using microprocessor for circuit control and gas monitoring to assure performance stability and reliability 3) Sounding a alert with 85dB at 10 feet 4) Test button to verify operation 5) Five-year limited warranty 6) Complies with EN 50291 standard 7) 4.5V battery, 12VDC, 24VDC, 110VAC or 220VAC available 8) Alarm: 70 minutes at 70PPM, 30 minutes at 150PPM, 9 minutes at 400PPM Packing: Box or blister card