The unit is easy to install, and screws and wall plugs are included. Conforms to BS 5839 pt6 Grade D, and also CE marked. Features a hush button for quieting false or nuisance alarms, and also a battery test button to ensure battery life is adequate. 

Optical alarms, also known as photoelectric detect smouldering types of fires, and should be used in living areas such as hallways, stairway landings and bedrooms. Do not use this or any other optical smoke alarm near kitchens or shower rooms. Measurements are 127mm in diameter, and 39mm deep. Manufactured by Kidde Firex.