This rule's 90° shape holds it snugly in place while the two scale surfaces allow you to measure and mark the top, edge and corners simultaneously. There are two vertical end scales with marking holes at 1/32˝ increments for drawing precise parallel lines relative to the edge of your work. Each rule edge has guide holes for fine dot marking at 1/32˝ increments. The center is slotted at 1/16˝ increments. The top edge is 7/8" wide and the other edge is 11/16˝.