This unit is powered off of a single, long-lasting, 9v battery that is included. On the face of the device, there is a dial that adjusts the sensitivity level to allow you to accurately locate even the most sensitive acupuncture points. The grounding rod and probe are chrome plated for comfort as well as easy cleaning for sanitary applications. The probe nib is small and can leave a comfortable impression in the skin to indicate the proper location for laser stimulation. This device is perfect for auriculo (ear) work and rivals units many times its cost.