The Solinst Model 105 Well Casing & Depth Indicator is easy to use when detecting metal well casing or measuring total well depth. It offers both of these functions without having to switch out the probe. The Well Casing & Depth Indicator is useful when determining where metal casing starts and ends in new or existing well constructions, hydrofracturing, and installing packers or other downhole instruments. The 105 Well Casing & Depth Indicator uses a dual-function stainless steel probe connected to clearly marked flat tape, fitted on a well-balanced reel. The probe has a strong internal magnetic assembly to detect well casing. When the probe is adjacent to magnetic metal (e.g. steel) a circuit is completed activating the buzzer and light (quick intermittent beeps and flashing red light). When the probe is no longer next to the casing, the signals stop. Depths are read from the tape at surface. A plunger at the bottom of the probe is used to measure total well depth. The light and buzzer activate when the plunger reaches the bottom of a well and is pushed into the probe body completing a magnetic circuit (slow intermittent beeps and flashing red light). The depth is read from the tape. The convenient battery test button checks the main circuitry to determine when the battery needs replacing. For easy-access, the battery is housed in a drawer in the front of the faceplate.