Ask our Italian Iridescent Ball Shank-Back Button in Oil-Spill Black to tell you your fortune! Resin cast, or plastic, buttons seem like glass but are a more durable option. Shank buttons encourage garments to drape and are an excellent choice for heavyweight fabrics. We are thinking about cardigans, coats, costumes, and more. This specific button comes in is size 15mm and in two other colors.