What do I need for punching larger holes?

If using the KOM350 or KOM400, the drive screw that is included with the kit (KS3540) is large enough so that the KC3540 is not needed. But for other applications a KC3540 converter needs to be used when using a cylinder/driver to punch a hole on any 3 ½” or 4” punches with the KPR7540 draw stud.