Perfect for adult coloring. They do not pierce behind the sheet (to water and not to the alcohol). I will not for a long time so no idea about using their lifespan. They are a bit expensive but the storage box is very convenient; it unfolds for a presentation of the colors straight. Thereafter I will redeem worn felts unit. The colors are well pigmented, I associated this format 88 (small point - 0.4 mm) for precision work, but points to the same product 68 (largest point) it allows me to keep the same colors, as well depending on the details of the same drawing I use one or the other point on the same coloring. I recommend
