This quartet is easily underestimated if its use is limited to the areas of application printed on it. It is far more productive to experiment with them. The leather cleaner can also be used to remove crayon marks from painted walls and clean worn wood. Scratched cell phone screens can be polished up quite nicely with the floor cleaner. Damaged CDs whose contents need to be saved can be carefully treated with the wallpaper cleaner, but with no guarantee of success. The erasers, which have different levels of abrasiveness, are also suitable for written and printed paper. They can be used not only on ballpoint pens (metal cleaner), but even - quite surprisingly - on the dreaded "ink pens", as long as the writing has not come into contact with water (leather cleaner). The wallpaper cleaner is recommended for pencils on sensitive paper.