The most Thread Checkers on the market are made of carbon steel, it may get rust after long term use. We upgraded it to alloy aluminum, light weight and will never rust.

• Gold Aluminum Plated Metric Thread Size: 13 Metric Sizes part numbers: M3X0.5, M4x0.7, M5x0.8, M6x1.0, M7x1.0, M8x1.0, M8x1.25, M10x1.0, M10x1.25, M10x1.5, M12x1.25, M12x1.5, M12x1.75.
• Red Aluminum Plated SAE Thread Size: Includes 14 Inch Size part numbers: 4-40, 6-32, 8-32, 10-24, 10-32, 12-24, 12-28, 1/4-20, 1/4-28, 5/16-18, 5/16-24, 3/8-16, 3/8-24, 7/16-14, 7/16-20, 1/2-13, 1/2-20.