The 4841 tool is a multi-parameter resistivity tool primarily used for oil/gas and water well logging.  The tool records four different parameters simultaneously in one pass of the borehole.  The four parameters are the following:  spontaneous potential, laterolog, deep and medium induction conductivity.  The induction curves are corrected for skin effect, and then converted to resistivity.  This tool is capable of recording a true resistivity (Rt) of the formation with the deep induction having a 65 in. (152.4 cm) depth of investigation.  It requires the use of the 4000 Stack Gamma Ray Tool Sub, which provides the needed telemetry, and is compatible with all other express stack tools except the 4239 inline litho-density tool.