For students or designers in the field. This lightweight drawing board has a built-in, locking, parallel rule. The removable straightedge is graduated in inches and can be locked into position either horizontally or vertically. The graduated protractor drafting head (optional) enables you to draw without triangles or protractors. Lock mechanism provides accurate drawing of perpendiculars, slanted parallels and cross-hatching. It fits easily on the starightedge and is graduated in inches. Locks at all angles. Automatic settings in 15 degree increments.