Originally designed for architects, engineers and draftsmen, these 12? triangular scales are ideal for Hobby Craft! The graduations, which are measured in Inches and Metric; are sharp, easy to read and are very resistant to wear! Plus, the triangular shape of these rulers allows them to stay put when they need to! Triangular Scales such as this one are pretty much the only way to guarantee a perfectly straight line! High-Impact Plastic with tapered edges. Item #902-110.