The legionary scutum, a convex rectangular shield disappeared during the 3rd century. All troops adopted the auxiliary oval (or sometimes round) shield (clipeus). Shields, from examples found at Dura and Nydam, were of vertical plank construction, the planks glued, and faced inside and out with painted leather. The edges of the shield were bound with stitched rawhide, which shrank as it dried improving structural cohesion. It was also lighter than the edging of copper alloy used in earlier Roman shields.