To prevent somebody from poisoning and far from danger Alarm density: carbon monoxide: UL2034 Interconnecting carbon monoxide detector Circuit for normally closed relay contacts Circuit for normally opened relay contacts Four models available for carbon monoxide detectors Operating frequency: 433/315MHz (optional) Power: 110, 220 and 230V AC (backup battery) Working temperature: -40 to 80 degrees Celsius Size: 166.26 x 90.26 x 36.50mm Weight: 300g/piece Quantity: 50 pieces/box Package size: 60 x 41.6 x 28.5cm Carton weight: 19.1kg