The invisible, odorless and deadly gas carbon monoxide can occur wherever there are combustion equipment such as open chimneys, gas boilers, water heaters, etc. Self-test function and voltage monitoring, acoustic and optical alarm, 85 dBA loud alarm tone, detection area: up to 60 m², 2x1.5V alkaline AA batteries, indicates when the battery power drops ("low-batt" signaling), tested and certified according to EN50291-1: 2010 + A1: 2012, operating temperature -20 ° - + 50 °