Alvin 6" rolling parallel ruler lets you measure in inches and metrics 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. Draws circles up to 12" diameter. Compass pivot button eliminates surface marking. Ideal for artists, students, pattern-makers, designers, quilters. Alvin #306 rolling ruler Includes instructions and many useful formulas and conversion factors.