You notice it getting dressed. The sock goes on fine over the toes and then catches at the back of the heel, and you have to work it past a patch of skin that has quietly turned into something else. Same thing under the sheets at night. That spot has been building for months and you ignore it because it does not hurt.

That patch grabs because the surface is not smooth any more. Dead skin builds into a thick dry layer, the top of it splits into fine ridges, and cotton hooks on those ridges the way it would on a rough board. Most people go at it in the shower with a stone, which softens the surface and leaves the depth where it was.

This is a sander, not a scraper. The head rolls against the skin and takes the dead layer down over several passes instead of lifting it off in one go. That is slower, and it is the point. On a part of the body where the gap between smooth and raw is thin, you want a tool that takes less per pass than you expect.

Work in short bursts and check with your thumb between them. The urge is to stay on one spot until the whole heel matches the rest of your foot. Two or three shorter sessions across a week get you to the same place without the tender stage in between. It also makes dust, so do it over a bin.

Two honest limits. It sands, and sanding is all it does: if the skin is hard because it is dry, you will be smooth on Tuesday and catching on your socks again a week later unless something goes on the foot after. And if you have diabetes or any loss of feeling in your feet, this is not your tool. Judging when to stop is a job your nerves are doing, and if they are not reporting, you find out too late.

It will not make your feet look like anything in particular. It stops them catching, which is the part you actually notice.