I used one of these for about a year (or a little bit more).
One side of the cover is a sharpening stone, the other a leather strop. The handle moves the blade back and forth over each side, in turn.
Wiki -
Rolls Razor . .Google -
Images
The handle and blade stores on the inside.
There's a nick in the blade but that causes no problems, I used it like that for over a year.
The last time I tested it (about 10years ago) it dry shaved hair off my forearm with ease. I still have it, somewhere.