My unit was put in by a anesthesiologist. Duke health in Raleigh, NC. No location for the internal power unit was ever discussed. Had to have it removed to different location. 48 staples were placed, because the anesthesiologist had no suturing skills. My experience is the high frequency (10,000Hz) does nothing to help. Had to switch to the 80 hz and this has helped but kills the battery in 3 days. Stay away from the Nevro unit. They are egotistical about the high frequency 10,000 Hz. Dr. J