The nipple barbell you see here has neither a thread nor any other locking mechanism. It consists of a 9/16" (14 mm) long and 14g (1.6 mm) thick bar with a tiny 0.02" (0.55 mm) hole at each end. In that hole fits a small pin attached to a ball. The ball is flat on the back and is approximately 5/32" (4 mm) high and 1/4" (6 mm) in diameter. In the center of the sphere sits a stone available in one of several colors that you can choose from.

The cool thing about this type of jewelry is that you can simply insert the small pin into the hole in the bar, and it will fit snugly into place. Over a period of time, the more you take it out and put it back in, the looser it gets. So if it becomes too loose one day, you can simply bend the pin a bit to give it more tension inside the bar.

This piece of jewelry is made of titanium, one of the best materials for piercing jewelry.