Features: 1.Best for drawing vertical lines, parallel lines, charts, angles, 3D drawings, horizontal lines circles, graps and musical note. 2.With horizontal line correction roller to keep your drawing paralleled. 3.With angle and arc protractor for you to measure angles. 4.With inspection magnifying glass to ensure the high precision. 5.The holes in each scale help you draw accurate vertical lines. specification:Condition: 100% Brand New Item Type: Parallel Rolling Ruler Material: Plastic Color: Clear Measurable Length: 30cm/11.8in 1.The Use of Protractor Align the center of the protractor with the apex of the measured angle, and overlap the scale of the protractor with the reference line to measure various angles on the ruler side. 2.Brush and Arc Curve Insert the pen into the small hole at the end of the ruler as the center of the circle, insert another pen into the other hole, and rotate the ruler body for 360 degrees to draw a circle. If the radius between the two holes is different or the ruler body is different, you can get different circle or arc. PackageList:1 xParallel Rolling Ruler