Using a magnetic switch, the Solinst Model 501 Well Casing Depth Indicator is well suited for measuring the depth at which steel well casing ends, which is useful when hydrofracturing. It also is useful for measuring the total depth of a well or for confirming well construction. The magnetic switch sounds a buzzer when passing close to metals. Available on Solinst flat tape with permanently adhered markings each 1¿0 foot or millimeter, the Model 501 gives accurate readings. The flat tape is constructed using stranded stainless steel conductors. These provide extra strength to support the heavy probe. Solinst Canada Ltd.