How does an electric foot file differ from a pumice stone?

It spins an abrasive roller against the skin, so it removes callus faster and more evenly than rubbing with a stone. The trade-off is that you must keep the head moving to avoid sanding one spot too hard.

Can I change the grinder head?

Yes. The grinder is interchangeable, so you can fit a coarser roller for thick heel callus and a finer one for smoothing. Check that replacement rollers match the fitting before buying spares.

Is it safe for thin or sensitive skin?

Use light pressure and short passes, and stop before the skin turns pink. A single-speed motor gives less control than a variable-speed unit, so test on a small area first.

Does it collect the dust?

No. There is no vacuum or dust chamber, so work over a towel or in the bathroom to catch the powder.

The tool itself with one grinder head fitted. Extra rollers are usually sold separately, so confirm what is included before you rely on a second grit.