At least one smoke alarm should be installed on each level of the home. The i9040 is a compact, 4-inch diameter alarm with ionisation sensor technology, and 3 years manufacturers warranty. The supplied batteries are not included as part of the warranty. A hush button allows nuisance alarms to be temporarily silenced. It can be wall-mounted (between 10-30cm from the ceiling) or if ceiling-mounted (at least 10cm from the corner with the nearest wall). The mounting bracket and fitting instructions are included ; easy to install and set up. These alarms are LPCB tested and certified to EN14604:2005, CE tested, and is fully tested before leaving the factory. View PDF for full product details. If you have a question that is not answered in the questions or PDF, please call Kidde on 0800 917 0722 (UK) or 1 800 818 601 (S. Ireland). Hush button operation. Test button operation. Batteries required: 1 x 9V (included) . Size H9.8, W9.8, D3.4cm. Weight 0.13kg. Manufacturers 3 year guarantee.