The kidde smoke alarm and carbon monoxide co alarm twin pack that protects against the dangers of co poisoning and fire the 900 0233 co alarm continuously monitors the level of co in the air and is easily portable meaning that it is ideal for holiday use 2 coloured leds determine safety green for normal operation and red for alarm mode the alarm can either be wall mounted or stand alone and has a testreset button the alarm has a long working life with a 7 year sensor life and a 7 year warranty