This is an excellent tool for both the drawing board and the workshop, providing a quick way to measure, draw, set or transfer angles. For layout work, you can set it to any angle from 0° to 180°, then use the 9" and 20" hinged arms (graduated in 1/16" and 1mm increments) as reliable reference edges to scribe your line.
In the workshop, it serves as a direct-reading angle-transfer tool. Its long arms permit accurate registration against inside or outside corners; a knurled thumbscrew then locks the arms in position so you can transfer the angle to paper or directly onto stock.
Made of aluminum with a matte black-anodized finish, it has crisply etched, white-filled markings for accurate reading, with angles in 1° increments marked in both directions for reading direct and supplementary angles.