Alvin - Adjustable Triangle - Computing Trig-Scale - 8 inch - The Computing Trig-Scale Adjustable Triangle by Alvin great to rise and slope graduations. This Adjustable Triangle has Inking edges on all three sides. Hot-stamped graduations. A thumbscrew locks the triangle securely at desired angle. The Computing Trig-Scale Adjustable Triangle is 0.12 inch thick, light blue, optically clear acrylic. 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.