Alvin Trig-Scale Adjustable Drafting Triangles, Computing Trig-Scale Adjustable Drawing Triangles

Quality Alvin adjustable drafting triangles with computing trig-scales feature 3 sets of graduations showing rise and slope from 0° to 90°. Desired angle is locked into position with a thumbscrew for accurate drawing. Strong 0.120" thick acrylic plastic is shatterproof light blue, optically clear. Inking edges on all 3 sides. Available in 3 sizes as shown. Detailed instructions included. Alvin LX-series adjustable drafting triangles.