Nut & Bolt Thread Checker (Inch & Metric) Each size has a nut and bolt checker on the same gauge. 26 male/female gauges - 14 inch & 12 metric. Thread sizes are permanently stamped onto each gauge (inch in red, metric in white) Inch gauges are clear zinc plated, metric gauges are black oxide. The individual gauges rotate freely on the wire cable for fast thread verification Wire cable with loop for convenient hanging