Expert Quality, for measuring of bore diameter and groove width. The spring - loaded plunger expands within the hole. Knurled locking screw allows plunger contacts to be held in position, removed and measured with a micrometer. Satin chrome finish. Supplied in PVC storage wallet with ranges marked. Features and BenefitsExpert QualityMeasures bore diameter and groove widthsLocking plunger contactsSatin chrome finish & storage wallet Contents 1 x Gauge range: 8 - 13mm (5/16 - 1/2") Length: 115mm 1 x Gauge range: 13 - 19mm (1/2 - 3/4") Length: 115mm 1 x Gauge range: 19 - 31mm (3/4 - 1.1/4") Length: 115mm 1 x Gauge range: 31 - 54mm (1.1/4 - 2.1/8") Length: 145mm 1 x Gauge range: 54 - 89mm (2.1/8 - 3.1/2") Length: 145mm 1 x Gauge range: 89 - 150mm (3.1/2 - 6") Length: 145mm