The disc is 2mm thick, thread - M2.5 - fits all systems with 2.5mm thread.
The threaded hole is slightly offset - this prevents the pendant (bead) from rotating on its own axis.
Possible size: 25 und 40mm - please select (selection box above)
Matching mandrels can be found here: cabochon mandrel
You can find this shape with the thread in the middle here
Material: stainless steel