These have been so useful to have on hand. We recently moved and are doing alot of decoratingId and, wall hangings, and just many different "projects". These are so great because they write on anything!!! Metal, Plastic, Glass, Painted walls, Stainless steel, wood, I mean literally anything!!! They are great for marking measurements, like when you are trying to hang pictures. You don't destroy the wall with permanent marker or strain your eyes trying to see a pencil mark. These are very dark and thick writing, but can actually be wiped away if needed! Another great thing is that you don't have to carry a pencil sharpener around with you because you just unroll the string like wrap to expose more of the marker! My husband loves these for cutting wood for building at home, and for his various labor needs at work.