The m Box door alarm is very easy to install & is completely wireless. A small magnet is attached to the door, & the transmitter itself is attached to the door frame. A built-in timer makes it possible to set the alarm for automatic operation at certain times. The m Box Door Alarm alerts carers if an individual with dementia leaves the accommodation, while authorised staff can simply press the bypass button to pass without activating the alarm. Please note this device is compatible with Care Tech systems only. Important note: This sensor is only compatible with Care Tech Carephones.