These cartilage studs come as a set of 5 in the colors shown (not randomly selected colors). Each stud is 1/4″ (6 mm) long with 4 mm balls. These are made with 316L Surgical Steel and Titanium IP plating. IP plating (ion plating) is a safe and permanent body jewelry refinishing process used to add color to body jewelry. This also creates a harder, shinier and more durable piece of jewelry.