Lead free Pyrex Glass is very strong. It is much harder to break than normal glass. All of our glass flesh plugs are hand blown. Glass and natural glass has been used for a very long time for flesh tunnels. Blue flesh tunnels made from carved Obsidian, which is a natural glass, have been found in Guatemala, which are over a thousand years old.
Some of these items are double flared. Read about double flared plugs on our ear stretching information page.