2-Point Inside Measuring Instrument Bore Gauge, 10-18.5mm, Graduation 0,01mm 511-204-20These are bore gauges that automatically self centre via a centring bridge. They offer you the following benefits: A long plunger stroke gives you amazing accuracy. Interchangeable washers 0. 5 mm thick are supplied as standard accessories, so you can enable setting in small steps. Contact points are carbide (>18 mm range), giving you high durability and wear resistance. A large grip reduces heat transfer from the operator by 50%. Specification Inch