This surgical steel labret has a base of 3mm. The top is internally threaded steel and brass and is pvd plated when colored and features a CZ butterfly 6mm wide and 5mm tall.
Because brass contains copper, it can oxidize with moisture or skin chemistry and leave a harmless greenish tint on the skin. It isn’t an allergic reaction, but it does make these pieces better suited for occasional or event wear rather than daily use.