1.Gauges:ring gauges 2.Material:GCr15 3.Type:Various types (Metric,UNC,UNF,BSW) 4.Precision:5H,6G,7H Metric ring gaugesFeatures: 1.Gauges:ring gauges2 ... .Material:GCr153.Type:Various types (Metric,UNC,UNF,BSW)4.Precision:5H,6G,7H 5.Measuring hole sizes and depths6 ... any question ,please feel free to contact with us. Metric ring gauges