These stylish & versatile body jewelry hoops from Forbidden Body Jewelry can be used in a variety of piercings. For nose hoops, the most common gauge sizes are 18g & 20g. A smaller, closer fitting hoop is 5/16 inch, and a standard size hoop is 3/8 inch. We strongly recommend measuring your piercing location prior to purchase to ensure that you choose the proper diameter, based on your individual piercing placement. Cartilage hoops vary in gauge size and can be 16g, 18g or even 20g. As with the nose hoops, 5/16 inch is on the smaller end, and 3/8 inch is a more average size diameter. Septum rings are usually 14 gauge and most people prefer a 3/8 inch diameter. Again, measuring is the only way to know for sure the perfect diameter for your piercing. As always, please contact us with any questions. We look forward to serving you!