Roll N Draw Ruler (16 CM & 30 CM) Used to Draw: Parallel Lines Horizontally. Parallel Lines Vertically. Square, Rectangle, Corners, Angles, Circles, Curves, & Arcs etc. Triangle Ruler: Ideal for plan drawers, architects, workshop, toolbox, home crafts, hobbyists, modellers, draughtsman, joiners, cabinet makers, card making , graphic designers, isomars triangular scale(T1) is a stylish rule suitable for architects 30cm / 12inch Triangular scale is made of white plastic with precision divisions and has color coded sides of red and yellow 1:10, 1:20, 1:25, 1:50, 1:75, 1:100, 1:125, 1:200, 1:250, 1:500, 1:750. Dimensions are in (cm) and (m) for easier working