Accurate reading - This folding parallel rule features transparent blades for easy reading with non-skid pads. Easy drafting - Sturdy aluminum links provide the right amount of tension for drawing a line parallel to another line or reference point. Premium quality - This folding parallel rule are made of durable materials including non magnetic and corrosion-resistant metal parts for long-lasting use. Ruler length - Each parallel drafting ruler opens to 3-inch spacing between blades and has 12-inch length. 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. Proudly Made in Taiwan