Abus hsrm20000 wireless smoke alarm device abus hsrm20000 p the abus hsrm20000 wireless smoke alarm device reacts to visible fire smoke within its detection range if an alarm detects smoke particles in the air all alarms in the building are triggered p p the wireless smoke alarm device is installed on the ceiling with a minimum distances to the wall of 15cm corners 50cm etc must be observed for details see the user guide we recommend a separate detector for each hallway stairca