The combination of ruler and protractor, semicircular protractor at the top can measure from 10-170 degrees left to right and right to left 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 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 Protractor and ruler of angles measure tool are precisions etching, the readings are clear and accurate, easy to read, wear resistant and for your use Round head protractor is suitable for engineering, angles measurement, student drawing, architectural designs, carpentry, length measurement, students, craftsmen, architects and designers, Manufacturer: Kaeltsyn