Very-quality mechanical pencil ....

Granted, for a mechanical pencil it is quite expensive but for "Good writers" as I am the pen is worth the money. He's been working very valuable and fits comfortably in your hand and I personally find the triangular shape with the knobs to be very pleasant. You can work with it without fatigue cramp. I use the pen with 2B mines and it works perfectly. The only drawback is the eraser in the cap. It has been my experience that it is really difficult for it to get spare and use this eraser therefore only in an emergency. But there are now prima Radiergummistifte that are not expensive.
Nevertheless: Who do not mind the high price for the pin gets a good-quality mechanical pencil. I can really recommend it.