I bought these for indoor use and have used them a few times. Since I haven't used them outside, they are only minimally dirty. The mesh material doesn't feel constricting, and since they have almost no heel, they are suitable for indoor shoes. They have a pump-like appearance, so they're not too casual and are easy to wear. The size is M, and they are roomy, so I think they are around 24cm. *Based on my own foot size of 35.5cm.*