The discs are 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.
A total of 8 discs:
cab_pl_15_1v, 20 and 30mm large,
cab_pl_15_2v, 30 and 50mm large,
cab_pl_15_3v, 30 and 40mm large,
cab_pl_15_4v, 30 and 40mm large.
Matching mandrels can be found here: cabochon mandrel
You can find this shape with the thread in the middle here
Material: stainless steel