12 is the gauge, 7/16ths is the size of the ring itself. Almost all body jewelry has 2 measurements. The gauge, like 16, 18, 14, 12, and then the size of the ring itself, 1/4, 3/8/ 5/16/ 7/16. I know the larger gauges are usually done in standard measurements, but with this stuff, the ring is both. 12 gauge, 7/16s across, and actually, these ones may be 1/2 inch.
I never thought I'd look right with one, so I never got it done, but I've done plenty, without a septum clamp they are a pain in the butt to do, in fact, that's usually how you can tell if they're done by a newbie or an at homer, is they'll be crooked as hell and through the cartilage, but they do look right on quite a few more people than you think, my homie CJ has like a 8 or a 6 in his, and it fits, I mean, it looks good.