There are many like, it but this one is mine. I have been in a never-ending search for the perfect pen. Ballpoints are cheap and dependable but in my humble opinion they write like crap. I just happened upon the Staedtler Pigment Liner. This pen comes in multiple sizes from 1 mm to .05 mm and colors.
The pen is intended for use in line art but works well as an every day writer. The pen is waterproof, lightfast and acid free, a perfect combination for Journals and sketching.
If you are interested in additional pen information check out Kevin Kelly. In his cool tools he lists pens that he finds satisfactory.