I got the 12 pack which comes with Black (2), Blue (2), Turquoise, Green, Clover, Coral, Orange, Hot Pink, Red & Purple. Admitedly the Clover is pretty light but a nice option.
I tried each fine tip, waterproof, acid-free, no bleed pens on the thin Filofax standard stock paper inserts, here is the front
And this is the back, with bright light on it. I'd say they did pretty well. Not only could you use these on paper where you would be writing on both sides but if you ever wanted to alter some plain ceramic dishes with doodles or a recipe on a serving plate, these would be perfect. Just write/draw/create on white oven safe dishes, bake in the oven for 15 minutes at 300° F to set the ink and enjoy of give as a gift.