A bore gauge is a measuring device for determining the interior size of a hole, cylinder, or pipe. In conjunction with a micrometer or master calibration rings, a bore gauge can give an exact reading of bore size. The measurement is derived by inserting the base of the bore gauge into the opening to be measured and moving the base gently until it exactly fits the diameter of the opening. The tool kit is consisted of03 No' of bore gauges with different ranges .