This compact carbon monoxide detector and alarm contains a sealed in battery with a 7 year life, and can be bulkhead mounted or used free-standing on the included base. It will emit a loud alarm when it detects carbon monoxide, even at levels as low as 30ppm. It is also small enough to be used when travelling to give protection from faulty appliances wherever you are. Dimensions: 100mm(H) x 65mm(W) x 30mm(D). Please note: This items does not comply with the Boat Safety Scheme.