Alvin 12" rolling parallel ruler lets you measure in inches and centimeters and draw quadrants, squares, circles, angles, crosshatching, and vertical and horizontal parallel lines, quickly and easily. Functions as a compass, horizontal ruler, straightedge, protractor, circle template and angle template, all in one. Unique compass pivot button eliminates surface marking. Ideal for artists, students, pattern-makers, quilters, and designers. Includes instructions.