Pro25, Stud Sensor With Picture Hanging Kit, Stud Scan Mode Locates Edges Of Wood & Metal Studs Up To 3/4" 19 mm Deep, Ready Light Indicates When Calibration Is Complete & Tool Is Ready For Use, Edge Arrow Illuminates When Edge Of Stud Is Located, Zircon's Patented Over Stud Feature Alerts If Scan Begins Over Stud, Spotlight Pointer Shines An Arrow Shaped Image On Scanned Surface To Clearly Indicate Edge Of Stud, "V" Marker Groove Enables Accurate Marking Of Stud Edge Location, Ergonomic Grip For Secure Hold In Either Hand At Any Angle, Uses 9V Battery Not Included.