Alvin - Engineer Triangular Scale Bamboo - 4 inch - These Alvin Engineer Triangular Scales are 4 inch professional-quality scales with a solid hardwood core, white, highimpact plastic laminated faces and tapered edges. Machine-engraved graduations and color-coded furrows. Supplied in plastic sleeve. 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.