Adjusting rings in steel C45 burnished, bore 20 mm with screws DIN 912 in steel 12.9. Shaft not damaged, greater holding force than adjusting rings, even distribution of clamping force, easy readjustment, absolutely precise bores. Screw thread DIN 912 with polyamide coating. Tolerance B: +0,08mm -0,25mm Temperature range: -40°C to + 175°C. 610 pcs.