Genuine Baltic Amber Plugs are tapered in, so that no O-rings are necessary to hold them in place. They are cut from Baltic Amber which is harvested one piece at a time by hand, along the shores of the Baltic Sea. Amber dates back 40 to 70 Million years, when there where dinosaurs roaming around, so it is fair to say that it is very durable, and has been in style for a long, long time.