Black circular barbell rings! Available in a range of gauges from 18G to 00G and diameters from 5/16" (8mm) to 5/8" (16mm), these Black PVD 316L stainless steel circular barbell rings are externally threaded. Note that the larger the size you choose, the heavier they will be. Sold individually - if you'd like two, mark quantity to 2.