Highly rated twin alarm pack for use in windows and doors in the home or outside buildings, easy to install and loud. Alarm and chime mode.
Possibly available at Amazon for same price but can't confirm if it's a Twin pack, image tends to suggest twin but description says 1http://www.amazon.co.uk/Friedland-Mini-Alarms-ML3-Magnetic/dp/B0041M8YBA
They are easy to install and simple to operate and they each come with a manufacturer’s one year guarantee. The Friedland ML 3 Magnetic Door or Window Alarms are sensors which mounts directly onto the door or window frame. When the contact is seperated, the alarm will sound. There are two settings: alarm or chime so this can be set accordingly and they come with warning stickers and self adhesive pads so no tools are required. Each pack contains two door/window alarms and each one comes complete with batteries. They are intended for internal use only.