Wire Gap Gauge. New Style spark plug wire gauge designed for longer and heavier usage. Contains 1 electrode bender and 8 wire gauges Equipped with knurled lock-nut, which releases the blades instantly for rapid selection of size desired When knurled lock-nut is tightened locks the individual blade into the working position, retaining the blades not in use firmly in the handle Sizes, both Decimal and Metric are permanently etched on each blade Made in the USA