Helix Professional Ruler - 18" Length - 1/16 Graduations - Imperial, Metric Measuring System - Stainless Steel - 1 Each Sold as 1 EA. Premium-quality ruler features etched graduations that allow dead length measuring in both inches and metric. The Imperial markings are in 1/16" increments, and the metric is in millimeters. Professional ruler is made of heavy-gauge stainless steel and features cork backing to prevent slipping.