Brand new 50mm diameter 4-jaw self-centering
chuck has reversible jaws.
You can select the WW style thread .270 x 40 fit most all 8mm lathes such as:
Bergeon, Levin, Derbyshire, Boley, American
Watch Tool Co., Peerless, Marshall, and most others.
Or metric size M7 x 0.75 such as Vector and
HOROTEC German brand.