Just a few notes about mechanical pencils I own.

Rotring Tikky 3

Functional but nondescript. The rubber grip is flush and held in place with indentations in the plastic body. So it doesn’t suffer as much from rubber degradation as the Staedtler Mars Micro 775 or the Pentel 120 A3DX, but it does deteriorate.
The large lead size is specified as 1.0mm, but standard 0.9mm leads work fine.
Third incarnation of the Tikky. Fixed lead sleeve, strong metal pocket clip and replaceable eraser under the polished button.