German Pearl Clasp Parts

Hi, I have a customer who has some pearls and clasps strung with a
spring loaded interchangable interlocking clasp. It’s really pretty
cool you insert the finely machined plunger/swivel end (which is strung
on both ends of the pearl strand) then push and twist a bit and it
locks in and swivels freely. The spring is in the middle of the tube
that runs the whole length of the ball or clasp box. The tube is open
on both ends and will accept the plunger on both ends. She got them in
Germany and would like to have more pearls strung with this type of
clasp. Can you tell me where to obtain these findings? Or have a source
of German findings that I can inquire at? Thank you John Caro
Jewelry By Design