This Home Protect Bedroom alarm is a long-life, optical smoke alarm with a sealed-in Lithium battery, that lasts the full 10-year life. Ideal for use in bedrooms it can either be wall-mounted (between 10cm and 30cm from the ceiling) or ceiling-mounted (at least 10cm from the corner with the nearest wall). The single screw mounting bracket, and full fitting instructions are included. Any question not answered in the Q+A or PDF call Kidde on 0800 917 0722 (UK) or 1 800 818 601 (S. Ireland). See PDF for full product details. A voice warning sounds alongside the loud, 85 decibel alarm, to alert when smoke has been detected. Research has shown that a voice warning is more effective at waking people, especially children, from sleep. A hush button means nuisance alarms can be temporarily silenced and an end-of-life warning signal alerts you after 10 years, when it's time to change. Certified by UL to EN14604:2005, CE tested and certified. Fully tested before leaving the factory. Hush button operation. Test button operation. 10 year sensor life. Batteries required: 1 x Li-Ion (included) . Size H13, W13, D3.3cm. Weight 0.18kg. Manufacturer's 10 year guarantee.