This single Stainless Steel Captive D Ring is made of top-grade 316L stainless steel and is available in ball sizes 3mm and 4mm. It features four available sizes, ranging from 18G to 14G, and inner diameters of 1/4" (6mm), 5/16" (8mm), 3/8" (10mm), and 1/2" (12mm). This versatile ring is suitable for many kinds of piercings, such as septum, daith, cartilage, and tragus.