The secret to the T-shaped square is a series of precision-machined index holes and close-tolerance, spring-loaded indexing pins engaged with it. The pin snaps into place, giving you confidence that it is precisely positioned. Even the most experienced woodworker faces the challenge of placing the angle precisely on a large panel project. You can try to extend the production line from a small protractor, but even a small error will cause the production line to extend further, the bigger the error. Our latest precision ruler can provide unparalleled precision for your panel layout work. Simply press the head to the desired angle, then press the straight line. The head can be adjusted from 0° to 70° and is firmly locked every 5° (plus 22 -1/2° and 67-1/2°) to provide you with precise reference angles and lengths respectively. It measures 10 inches Even if you don't use angles, this is a layout tool that can be used in almost any project. The blade has the same exclusive serration feature. Design notches are found in our new product. Stainless steel precision woodworking square. Simply place the pencil in the notch and slide the head along the edge of the stock for a perfect parallel line.