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; Accuracy 0.005MM;Quickly locate work edges;Probe Hardened & Ground;Not necessary to rotate while measuring; 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 , outside & inside circle diameters can be detected;, Weight: 5.3792791928 pounds, Manufacturer: Kueohse