My Master won't let my nipples be pierced, but the good news is that they're large enough for non-piercing rings and shields. The bad news was that they weren't big enough to always keep the rings or shields on, and the punishment for letting them slip off was an evening chained to the wall with my nipples in clover clamps and my balls in the crusher. But a week or so back he got me the nipple enlargers, and after only a few sessions my nipples were big enough to hold the shields on firmly. They don't even come off now when I'm sucked: fantastic! I can't recommend them too highly.