Ear Post Earring Post. The flat pad ear post can turn almost any flat backed item into a pair of beautiful earrings. Just glue item on to create unique earrings. A metal allergy is an allergic reaction to metal, usually referenced in the form of jewelry. Although different types of metal can cause allergies, most people who experience allergies react to nickel. These posts are nickel free so are an option for those sensitive. Size: Ear post - 12mm long, Pad - 6mm