Clear plastic protractor is ideal for all young mathematicians. Protractor features an open center. Students will easily be able to identify angles from 0 to 180 degrees with the protractors sharply defined graduations which is easy to read and helps minimize visual errors. Ruler Base—Metric and SAE graduations along 6" ruler base. Degree Graduations: 1°; Material(s): Plastic; Ruler Size: 6" Ruler Edge/180°; Color(s): Clear.