62168/62167 STUD SENSOR Z-CARD | Locates the wood or metal studs up to 3/4 in deep. Red LEDs light up every time a stud edge is approached. An audio alert and green LED signals when the stud edge is reached. Should scanning begin over a stud, over-the-stud indicator alerts the user to start the scan in a new location. TruCal technology calibrates to any wall's density and a steady green LED TruCal light alerts the user when the tool is calibrated and ready to scan.