The Lamy CP1 Twin pen is a little bit different.
It contains a black M21 ballpoint refill and a 0.5 mm lead mechanism with a built-in eraser underneath the removable button. Each function is selected by a twist of the upper barrel and is shown by the system identification ring.
This model features a slim, modern and understated looking body with a tough and stylish matte black steel finish and gloss black pocket clip.
Additional ballpoint M21 refills available here.
Additional leads available here.