Color variety is great as well.

these pens are top quality, has clean lines and good for markingand has nice color too

The ink does not smear as well

If you are the black-and-blue-ink-only kind of person, Pentel also sells a more conservative package of pens with only those shades, and they work great as well

If you like the regular blue/black/red Pentel pens, then you will feel the same way about these pens as well.