Surface of the rulers are smooth with no burr, with a hole to make it easy for hanging, storage.Which keep your things organized This straight ruler is a useful measuring tool for artists, designers, architects, engineers, and students Ruler is 0.7mm Thicker A+ stainless steel non-bendable but a little flexible, good for long lasting use The markings are recessed a bit into the metal, so they will not rub off over for time engraving, concave scale design, with metric on side and on the other end Suitable for any environment, can maintain accuracy for a long for time, Manufacturer: Oxxggkao