Material: Steel C45, black oxide finish. Screws steel 12.9.

Features: does not damage the shaft, stronger clamping force than
with set collars, even distribution of clamping forces, easy
readjustment, precision honed bores. The threads of the screws DIN 912
are covered with a layer of polyamide. Tolerance b: +0.08mm -0.25mm .
Temperature range: -40°C to +175°C.

Remarks to collars from steel:
The black oxide on the clamping
collars is formulated as part of the total performance of the product.
It enhances the holding ability of the collar, it efficiently reduces
slipping on the shaft, has anti-stick-slip characteristics and helps to
keep the torque rating of the screw within its designed parameters. The
oxide layer also provides corrosion protection.