Blue is a color that the overwhelming majority of pen users would want for everyday use, from quick notes to long texts. This particular product certainly offers a very good quality-price ratio, but I don't think it can withstand serious use. It fades on paper within a few weeks. If it is intended for casual use (e.g. notes that will be thrown away anyway), it is a great economical solution! Another positive aspect is the easy washing in case of accidents or pen cleaning (here the low saturation it has in dye helps).

Exactly what I wanted.