SK Retention Knob Pull Stud.Pull studs of minor quality not only decrease the performance of the machine,they are even a safety risk.A breaking pull stud might cause severe damage on machine and workpiece and even injuries on persons. Specifications 1, Material: 20CrMnTi 2, Pull stud is mainly used for connet the tool spindle and tool holder 3, the type: BT pull stud, SK pull stud, ISO7388 Pull stud, CAT pull stud, Mazak Pull Stud, MTB Pull Stud, NT pull stud 4, hardness: 52-58HRC 5, Surface blackening, grinding 6, Total Length:54mm, screw: M16 7. Type: D40 /SK40 8. Used for DIN40 Tool Holder 9. Costly heat treatment in several steps 10. Spots with highest stress tempered specifically 11. High impact strength 12. Precision can reach 0.015mm 13. Highest security and reliability 14. Suit for mill chuck holder 15. All critical pull stud surfaces precision ground. …