High quality material: The roof triangle protractor is made of aluminum alloy, which is anti-corrosion and anti-rust. The surface is matte black, smooth to prevent glare, and the scale is clear and easy to read. [High Accuracy]: The carpenter's square ruler comes in metric and inch sizes, with clear and accurate scales, 0-90 scale, printed inch scales and ordinary conversion tables, easy to measure and read. Multi-purpose in one machine: The triangular ruler can be used as a protractor, miter, saw guide, plotter, three meter ruler, frame ruler and ruler. Multi-use for one machine: The thick triangular edge of the ruler can be used as a saw guide. An engraving protractor can be used with a saw to make side or miter cuts against a square. Application: The Aluminum Carpentry Square can meet the needs of hobbyists, home builders, fabricators, DIYers, artists and woodworkers.