The older model Lumber Wizard Woodworking Metal Detectors (before Lumber Wizard 5) had manual tuning in order to maximize the detection depths for finding nails, screws, wire, etc in reclaimed wood. To tune, be certain you are using a brqnd new quality fully charged 9volt battery then turn the Lumber Wizard on and adjust the fin tuning screw to the point right where beep stops. At the point where beep stops when turning the fine tuning screw the gree light should flash every second or so and the detector will detect when passed over a small piece of metal.