Measure - Deeply etched scale reads forward and reverse from 0 to 180 and will not wear or rub off ADJUSTABLE - Adjustable protractor arm locks into desired position with knurled thumb nut for quick and easy angle identification Durable - stainless steel for precision, strength and rust resistance ESSENTIAL TOOL - Ideal for students, mechanics, carpenters and woodworking enthusiasts to set bevels, measure and transfer angles feature: 1. The protractor with adjustable arm is made of durable stainless steel, ideal for setting bevels, taking measurements and transferring angles. 2. This round head protractor has a semicircle scale from 0 to 180 in the forward and reverse directions, which can measure all angles. 3. Measure angles with a small stainless steel arm that slides smoothly for precise alignment. Use the knurled thumb nut to lock the measuring arm in place while taking measurements. 4. Its stainless steel construction gives it strength, durability and rust resistance.