Just a few notes about mechanical pencils I own.

Pentel Twist-Erase III QE519

Slightly stubby but easy to hold. Good rubber grip, quality plastic barrel, steel cone and strong reliable steel clip. The extra-wide and extra-long replaceable rubber eraser is uncapped, but twists completely into the top housing. Pentel claim that it is non-smudge, and it certainly is good.

A perfectly serviceable simple pencil with no special features other than the quality eraser. Available in standard lead thicknesses and different coloured barrels.