The Ei208 is a high powered alarm, powered by a sealed-in Lithium battery, incorporating a proven electrochemical sensor to sense CO presence. Stringent testing and calibration in CO gas ensure its accuracy. - The unit can be easily fixed to a wall or ceiling due to the twist on mounting base which has multiple fixing points. - An easy to use Test/Hush button ensures that the user can test all aspects of the alarm and a memory feature records the last CO level sensed which enables the user to know if CO has been recorded during any absence from the property. - Operation - If the alarm senses the presence of CO an audible alarm will sound and a red alarm light will flash.