Safe-T 46110 mmArc Protractor Compass Plus - Pack of 1 - Made of Clear Plastic with Bluish Hue, 15.8 cm long, Semicircular side with rotating disc inset on one edge, Spinning & Accurate Protractor revolves easily within a groove, Creates Circles from 10mm radius to 120mm radius on 1mm radius increments, Allows direct view of vertex points, Straight Edge sides have inch/metric scales, Works well with Vis-a-Vis or other felt tip pens, Can be used with Rightstart Mathematics, Safe for Children