Alvin - Tru-Angle - Adjustable Triangles - 12 inch - Alvin Tru-Angle Adjustable 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 half a degree accuracy. Tru-Angle Adjustable Triangles have die-engraved graduations for high visibility. The aluminum thumbscrew securely holds the selected angle and allows quick pickup and manipulation. Tru-Angle Adjustable Triangles are made of high impact, 0.100 inch thick, optically clear acrylic to eliminate parallax and allow close pencil tolerance. Alvin is one of the primary sources for drafting supplies and drawing equipment in the country. Creative Coldsnow is a pround retailer of Alvin graphic arts, drafting and fine arts products.