Alvin Tru-Angle protractor drafting triangles provide the features of a 45/90 degree adjustable triangle plus those of a protractor. Angles from 0 to 90 degrees can be drawn from the baseline with 1/2-degree accuracy. Die-engraved graduations for high visibility. The aluminum thumbscrew securely holds the selected angle and allows quick pickup and manipulation. These adjustable triangles are made of high impact, 0.100" thick, optically clear acrylic plastic to eliminate parallax and allow close pencil tolerance. Available in 4 sizes, with or without inking edge. Alvin Tru-Angle adjustable triangles are made in the USA.