In the Peugeot Bistro Chef Salt & Pepper Mills, 4", the pepper mill uses a case-hardened-steel mechanism, while the salt mill uses a stainless-steel mechanism.
Yes, the knob lets you adjust the grind from fine to coarse.
The top knob is marked with an “S” or “P”.
Turn the head of the mill clockwise to grind.
The pepper mill’s case-hardened-steel mechanism cracks peppercorns before grinding for even grind and rich aroma.