Ceramic hard wearing top quality mill mechanism. This design needs no adjustment knob at the top of the mill (it is at the bottom) allowing you to make elegantly shaped mills up to about 320mm high.
The mill outer stator push-fits into a 38mm hole at the bottom of the mill body. The top driven component requires a 22mm hole in the wooden top of the mill. Little plastic hooks are meant to click into a recess to retain the components but if you prefer you can just glue in the parts.
These are very easy to cut down to your size. Just cut off a section of shaft with a hacksaw and bevel the cut end with abrasive so the the top of the mill pushes on smoothly.
The image is of the 190mm mill. The 297mm is the actual length of the mechanism from the top of the shaft to the bottom of the projecting adjustment knob. You would add about 15mm or 20mm to this for the actual wood casing to allow for clearance at the base for the knob and the thickness of the wood right at the top.