General protractor is used for setting bevels, measuring, and transferring angles. Durable stainless steel construction. Deeply-etched graduations from 0 to 180 degrees in both forward and reverse directions and will not wear or rub off. 3.375" x 2" head. 6" adjustable arm locks in position with knurled thumb nut. Perfect for students, machinists, carpenters, and woodworking hobbyists. General #18 round head steel protractor with arm.