Chrome-plated steel. Locking knurled handles and automatically self-centring plungers with constant spring tension for uniform contact pressure. Quick inside measuring of cylinder or hole bore by transferring dimension for external measurement. Indirect measurement by outside micrometer. Includes: 8 – 12.7, 12.7 – 19, 19 – 32, 32 – 54, 54 – 90 and 90 – 150mm gauges. Chrome-plated steel. Locking knurled handles and automatically self-centring plungers with constant spring tension for uniform contact pressure. Quick inside measuring of cylinder or hole bore by transferring dimension for external measurement. Indirect measurement by outside micrometer. Includes: 8 – 12.7, 12.7 – 19, 19 – 32, 32 – 54, 54 – 90 and 90 – 150mm gauges.