Every gauge carries a calibration certificate giving actual values, Highly versatile 18-50mm bore gauge covers a large range for which one needs to generally purchase 2 bore gauges having ranges Ø18-35 mm and Ø35-60 mm, High wear resistance due to carbide-tipped fixed and moving anvils Wide bridge ensures automatic centering in the bore, Self-centralizing feature of this bore gauge ensures that measurement can be done with minimum skill, Supplied in a sleek wooden case containing measurement anvils and extension rods with necessary tools