Broad measuring range for versatile use 5/16 inch to 6 inch (8 mm to 150 mm) internal diameter measurement capability, suitable for a wide range of industrial and automotive applications. Each gauge extends into the hole or recess, then locks and is measured with a micrometer or caliper for precise readings. Consistent, reliable readings Engineered with constant spring tension to maintain uniform contact pressure during measurement. This helps deliver repeatable, accurate results, making the set valuable for quality control and engineering tasks. Durable, construction Chrome plated for enhanced durability and resistance. The bright, reflective finish adds to tool longevity and helps withstand demanding environments over the long term. Comprehensive set with organized storage Six telescoping gauges included, neatly organized in a robust storage box. This arrangement protects the tools and simplifies transportation and storage, making it a practical choice for professionals on the move. Practical use scenarios Measuring internal bores in engine cylinders, sleeves, or housings to verify bore size and consistency. Checking internal recesses such as valve guides, bearing seats, and pockets during machining or assembly. General internal dimension checks in fabrication, , and quality control processes to ensure parts meet specifications.