The ProSensor M155 is a high-accuracy stud finder with 9 precision sensors. In comparison, conventional stud finders have only 1 or 2 sensors. With more sensors, the ProSensor M155 more accurately detects studs with no calibration required. The precision LED display shows the FULL WIDTH of studs, double studs and irregular configurations other stud finders cannot detect. The M155 also features live wire detection for added safety as well as a center stud indicator.