The ABUS Door Sensor Contact can be used to extend your ABUS Smartvest wireless alarm system. The sensor is used to protect windows and doors by activating the alarm siren when the door sensor contacts are separated. For use with: ABUS Wireless Alarms ABUS Smartvest Wireless Smartphone Alarm What's in the box? 1 x Door Sensor Contact *This sensor is suitable for most doors and windows and should be fitted with a maximum space of 10mm between the sensor and magnet. We advise checking metal or UPVC doors and windows for compatibility.