Fangrui Product Details Accuracy 0.005mm;quickly Locate Work Edges;probe Hardened Precision Ground;not Necessary To Rotate While Measuring; Led Lights Instantly And It Beeps When Probe Touches Conductive Work Piece;there Is A Safety Spring Puller Which Puts The Ball Precisely Back To The Position When Ball Breaks Away From Ball Seat; These Excellent Tools Quickly Locate Work Edges And Save Time When Finding Positions On Milling Machines, Jig Borers Etc Etc; They Employ A Highly Sensitive Location Sensor And Utilize A Red Pilot Light Which Can Be Clearly Seen And An Audible Beeper The Location Of The End Surface, Outside Inside Circle Diameters Can Be Detected; Shank Diameter: About 20mm Item Length: About 160mm Ball Diameter: About 10mm Battery: 2 X Lr1/1.5v/n Alkaline Battery (size N/lr1/1.5v) (not Included) Color: Silver Material: Steel Package Included:1* Electronic Edge Finder With Original Box Only The Above Package Content, Other Products Are Not Included. Note: Light Shooting And Different Displays May Cause The Color