Motion Sensor with Remote Alarm No alarm noise in room where the motion sensor is placed. When the motion sensor is triggered, it sends a signal to a remote alarm which can be up to 100' from the motion sensor. Motion sensor can be mounted to the wall or floor, or simply placed on a surface using the built-in stand. Remote alarm has 3 volume levels and an on/off button. Motion sensor requires 3 AA batteries, and remote alarm requires 3 C batteries (not included). Or, purchase with Kerr AC Adapter AC-04E (sold separately), which is compatible with both the motion sensor and remote alarm, to use less batteries over the life of this product.