Precise Sketching - Quick yet detailed sketching with this Parallel Straightedge Bar. Featuring rollers that retract at a touch securing the blade for accurate drawing Easy Installation - Each Parallel Straightedge consists of all mounting hardware and easy-to-follow instructions leaving you with everything that you need to assemble this tool. Easy and Ergonomic Use - Acrylic edges are elevated to prevent ink smears while steel ball-bearing pulleys provide smooth ergonomic movement Durable Construction - This parallel straightedge features a rigid phenolic construction with a black satin finish for a sleek yet durable ruling A Professional s Choice - Alvin has been the professional s choice for drafting tools and drawing supplies for over half a century. Since 1950 we have brought quality and value to our customers. Our tools help bridge the gap between ideas and innovations. We are known for our wide selection of high quality tools at a fair price. Proudly Made in Poland