Bullet Ring Design Unisex. Sellier&Bellot .357 Magnum used bullet and recycled to become a piece of jewelry. Adjustable size and high polish finishing. Description: Face diameter: 12.50 mm Bullet approx diameter: 10.90 mm Band width: 4.30 mm Material: 316L stainless steel casting Stainless Steel is a great metal for jewelry in general. With one of its best propriety that is hypo-allergic makes a great choice for someone with sensitive skin. You will find that stainless steel with not turn green or any other color will not tarnish or rust, due to its high resistance to corrosion, is durable and resistant to scratch. Stainless steel requires little or almost no maintenance to keep looking as new. In case of accidental dirt, it will retain its luster using a mild detergent dissolved in warm water and then dry it with a piece of soft cotton cloth.