You'll fall in love with chain maille supplies by Weave Got Maille, including these 18-gauge jump rings with a 4mm I.D. (inner diameter) and a 6.1mm O.D. (outer diameter). Choose from a large array of vivid enamel colors that are durable and more reliable than anodized colors. Made in the USA, the combination of copper wire and brilliant enamel coating results in jump rings that are easy to manipulate and hard to scratch. Jump ring sizes follow the American Wire Gauge (AWG) system of measurement, sometimes known as the Brown and Sharpe (B&S) system. All enamel colors are tumble polished to give them a bright and shiny appearance.