These versions of Burt have their tongues sticking out. Version one has hole that allows a jump ring to be added. Version two and three both have holes that go through the body. This will allow you to add a small bead to the inside of the mouth by using a earring head pin. Version 2 has a larger hole that is 2mm and version 3 has a hole that is 1.2mm. Please note that these holes may differ depending upon your printer.

To get a good print of these files, you will want to use a .12 or smaller layer height.

We used the following jump rings for version 1 of Burt https://amzn.to/4mA1zTn