These come in either ASTM F-136 or F-1295 Implant Grade Titanium or ASTM F-138 Implant Grade Stainless Steel
These come in different gauge threading and different size beads
Threaded barbells or threaded posts(not included) required for wear
If you do not know the gauge or size you need, do not guess. These are not a small, medium, large-type of sizing. These are very barbell size specific and if you are incorrect the bead will not work.