brush pen & pencil crayon
This is my Pentel Pocket Brush GFKP. It's one of the best pens I've ever used for sketching. The tip is very fine and flexible and the ink is permanent and fade resistant. It saves me from having to set up my pens, brushes and bottle of ink each time I feel like doing a quick sketch. I've made it look a little bit stumpy, but it was a quick sketch.