I was introduced to Frxion by a friend who really likes stationery some time ago. I have about 3 different versions of this pen. And yes they are really good for knitting!
Frixion is a line of erasable ink pens by Pilot. It comes with hard plastic eraser, that uses friction to erase the ink. The best part is it comes a multitude of colours and styles. I personally like the ones in interesting colours like orange, pink, purple and green. I just wish they would also stock the refills for these interesting colours, refills tend to be red, black and blue – the usual colours. There are various permutations to the line up, fine line, rollerball and even felt tip. The pen also comes in different styles, with a cap, multipen and retractable.
The ink erases clean most of the time. When it doesn’t, I find that a normal pencil eraser works quite well to remove marks that were left behind.
I find these pens great for marking rows on knitting patterns. This works great for crochet patterns with symbols too! The bright colours show up better than pencil and the ink erases cleanly when I make a mistake and have to redo. It also works great for calculations and notes in general because you can make corrections as you engineer a project.