GROZ DP6 DEGREE PROTRACTOR – GZ01220 Manufactured from stainless steel the Degree Protector comes with a semi-circular head. The head has permanent deep etched graduations 0 to 180° in opposite directions thus permitted reading an angle directly and also its supplement. The 6 (150mm) blade has a graduation line on one end that permits accurate setting and reading of angles. The blade can be firmly set at the desired angle by means of a knurled nut. Angular Tolerance: ± 0.5°