Protractor with integrated swing arm that rotates 180° for super accurate and easy visual angle measuring. Great for younger students who are learning how angles work. The Swing Arm Protractor is made with shatter-resistant materials for safety. Protractor body features integrated 6" and 10 cm rulers and a dual-graduated top curve so angles can be measured left to right or right to left. Transparent plastic makes it easy to see what you are measuring, and included beveled edges make for easy manipulation.