BCP 30CM / 11.75INCH Multi-purpose Rolling Parallel Ruler , Parallel Glider Multi-functional,can be use as for compass, horizontal ruler, straightedge,protractor, circle template and angle template Combination rolling rulers, good for drawing verticallines , parallellines,charts, angles,3-d drawings,horizontal lines,circles,graphs,musical-note Ideal for artists, drafting students, pattern-makers, and designers Total Length :30cm / 11.75inch