Provides the features of a 45°/90° adjustable triangle plus those of a protractor. Angles from 0° to 90° can be drawn from the baseline with ½° accuracy. Die-engraved graduations for high visibility. The aluminum thumbscrew securely holds the selected angle and allows quick pickup and manipulation. Made of high impact acrylic that is 0.100" thick and optically clear to eliminate parallax and allows close pencil tolerance. All sizes have inking edge.