Three Sizes Available: 10", 15" or 20". Both edges of the blade are engraved with inch graduations in 1/32" increments. The scale has a total cumulative error of 0.004" over the blade length. The thin satin steel blade is easy to read and minimizes parallax errors.Unparalleled precision: Our latest precision scale can provide unparalleled precision for your panel layout work.Just press the head to the desired angle, and then press the straight line.The head can be adjusted from 0 to 70 and fixed every 5 (+22-1 / 2 and 67-1 / 2), in order to provide you with an accurate reference angle and length respectively.Both edges of the blade are engraved with an inch scale of 1/32 inch. Increment.The total cumulative error of the scale over the blade length is .004".The thin satin-finished steel blade is easy to read and minimizes parallax errors.Just place the pencil in the notch and slide the head along the edge of the stock to get a perfect parallel line. SIMPLE OPERATION: You can make the cross of the disc next to the edge of the board, then turn the ruler to get the angle you want. Adjust the nut to get the best feel. Place the tip of the pencil in the saw tooth notch and then move the ruler along the edge of the board to get different parallel lines. In short, you can draw any line you want with this ruler