Features:Accuracy 0.005MMQuickly locate work edgesProbe Hardened & Precision GroundNot necessary to rotate while measuringLED lights instantly and it beeps when probe touches conductive work pieceThere is a safety spring puller which puts The ball precisely back to the position when ball breaks away from ball seatThese excellent tools quickly locate work edges and save time when finding positions on milling machines, jig borers etc etcThey employ a highly sensitive location sensor and utilize a red light which can be clearly seen and an audible beeper The location of the end surface, outside & inside circle diameters can be detectedSpecifications:Shank Diameter: about 20mmItem length: about 160mmBall Diameter: about 10mmBattery: 1 x 23A/12V Battery (10X28.3mm) (Not included)Head Material: SteelCover Material: IronPackage Included:1x Electronic edge finder