Alvin - Rolling Ruler - 6 inch - Alvin Rolling Ruler is a multi-purpose drawing tool made from high-impact plastic for students, artists, and designers. Graduated in both inch and metric. The Alvin Rolling Ruler includes many useful formulas and conversion factors. Draw horizontal and vertical parallel lines with ease. Draw circles, curves, or arcs. Use the built-in protractor to draw angles. Blister-carded, instructions on back.