If I don't take care of my feet every day I develop really hard, hurting calluses underneath my feet. I've tried a lot of different foot files in the budget class, but non works quite as well as this foot smoothing stone.
It is recommended that you use it after having bathed your feet, but I find it works much better on dry feet, before the bath. Just go in circles where you want to rub the dead skin off, and your feet will soon be baby smooth.
The negative aspects is: it becomes dirty quick, hard to clean and wears down easily. Nice to look at, great that is is made from recycled materials, but frankly I prefer other foot tools.