Precision ground, quenched, and tempered.
All popular heavy-duty chucks manufactured by Schunk, Forkardt, Röhm, and SMW (with sharp serrations).
Forkardt: NH 160-200, NHF 160-200
Schunk: TH/THF 165-210, HSL 165-210
SMW: HFKS 160-200, HFK 160-200
Socket head screws DIN 912 - 12.9!
Other T-nuts available ex works.