Why the rolled edge?

While military spec dog tags are quite durable, they are surprisingly thin. Without the rolled edge the edges of the tag would be quite sharp. The rolled edges also add a bit of rigidity to the tags to keep them from bending. Rolled edges came into use during the WWII era and allowed for a much lighter, thinner dog tag that could be embossed instead of engraved. The embossing let a much deeper and easier to read mark on the tag.