[Clear Marking] : There is a small hole at both ends, which is convenient for adjustment and disassembly with screws. You can easily rotate the thread pitch gauge blade where you press the tooth thread gauge. The numbers are clearly marked and easy to read.[Material] : Screw gauge tool set is made of stainless steel and processed with chrome finish. Surface polished smooth, applying anti-rust oil to prevent rust.good resilience, elegant appearance.[Measuring Range]: 51 pcs America SAE type measuring range is 4-84; 52 pcs Metric & America SAE Type & British Whitworth Metric is 0.25-6.0mm, Imperial is 4G-62G US: 8, 10, 11, 14, 19, 28.[Suitable Scenarioos] : Thread pitch gauges set usually used to check whether the size of the mold, machine and mechanical thread is correct; use thread gauges blades of different sizes to accurately measure internal and external threads; center gauge is used to grind and position thread cutting tools on a lathe.Colour:silverMaterial:Stainless steelPackage Contents:1 x American SAE type pitch gauge 60 degree,1 x British Whitworth metric system pitch gauge 55degree 2 x center gauge 60 degree1 x center gauge 55 degreeOnly the above package content, other products are not included.Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.