The combination of ruler and protractor, semicircular protractor at the top can measure from 10-170 degrees left to right and right to left. Protractor and ruler of angles measure tool are precisions , the readings are clear and accurate, easy to read, wear and convenient for your use. Angles finder protractor crafted from carbon steel, with well durability and wear resistance, not easy to rusts, and can apply for long time, but notice that the peaked carbon steel border, please be careful while using. Adjustable protractor arm: angles is quickly and easily identified by knurlings thumb nut locking in the desired position, you can fix the angles to plot, suitable for setting bevels, draw radials lines, measuring and marking angles. Round head protractor is suitable for engineering, angles measurement, student drawing, architectural designs, carpentry, length measurement, for students, craftsmen, architects and designers. Colour:As Shown Material:steel Size:150x300MM Package Contents: 1 * Carbon Steel Protractor Only the above package content, other products are not included. Note: Light reflection 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.