By selectively filtering out 60Hz (or 50Hz) and its harmonics, the 200FP can be used with any tone generator for faster, more accurate, cable and wire identification. Slim, comfortable design for use in limited-space areas. Recessed on/off push-button control to conserve battery life. Adjustable sensitivity/volume control to increase accuracy. Blended carbon/plastic tip to reduce the risk of shorting terminals. Patented.