Features Precise grinding: The 2 ends of the bore gauge are made of head treated steel and are precisely ground to a certain radius so that they will fit properly in the smallest hole the gauge goes into. Quality: The T-Bore Hole Gauges is firmly fixed on the contact plunger and self-centering automatically. Constant spring tension provides uniform contact pressure. High quality, high rigidity, good wear resistance and durability. Operation method: expand the Precision Telescoping Gage in the tested hole, lock it in place, then take it off, measure with a micrometer or caliper to determine the final hole size. High performance: Rigid handle and double-acting design (automatic centering) can quickly check internal dimensions. The spring tension is constant and the hand feels even. Application: Bore Gauge used to obtain the accurate size of the hole and slot, suitable for factories, schools, offices and other places. Features: Double action handles are rigidly attached to the contact plungers and are automatically self-centering.Assist in quick checking of holes, slots and recess up to 6 inch deep.The ends of both contact are head treated steel and precision ground to a radius allowing proper clearance on the smallest hole the gauge will enter.Constant spring tension delivers uniform contact pressure.Super quality, high rigidness, good wear resistance, durable in use. Specification: Condition: Brand new Material: Tool steel Color: Shown as picture Measuring Range: 8-150mm Accuracy: 0.1 Quantity: 6Pcs/Set (ABCDEF) Scope of Application: Telescopic spring piston in the hole (or groove), can conduct inner diameter detection, used with micrometer or caliper, with knurled locking device. Package List: 1 Set Telescopic Gauge (6pcs) Package List