The 200FP Filtered Tone Probe is designed to identify and trace wires or cables within a group without need of removing insulation. In addition, the 200FP has been specifically designed to filter out all power-related noise to eliminate “Power Line Hum.”The unit is constructed of durable ABS plastic, and an optional leather carrying case, 200C, is available.The 200FP is also available as part of the Model 801K kit.