This 18" stainless steel ruler has a cork bottom to provide a clean raised edge. Stainless steel will last a lifetime, and won't get pitted and worn on the edge like plastic rulers. Includes both standard and metric measurement units. Sold as a pack of 6 rulers. 18" Stainless steel ruler with cork backing is the highest quality! Standard and Metric Measure. Long-lasting stainless steel. Cork backed to hold steady. Easy to use as a drawing straight edge or measuring. Perfect for home, school, and office. Age: 4+ years/Grade K-12