Martin Pro-Draft Parallel Edge Board Drawing Kit, Small The only parallel straightedge board utilizing an anti-warp aluminum body straightedge for strength and stability Deep ribbed strips so that the unit can be adjusted over the table edge to bring the artwork into the users lap Locking device to lock in any angle that you would like to draw Each side of the unit has large knobs for adjusting the straight-edge to align with the artwork/drawing and stay parallel High resin particle board to prevent board breakage