I just bought one. It's a loofah, made from a loofah/luffa gourd (Luffa cylindrica). They skin it and cut it into a chunk. It exfoliates a lot rougher than gloves, beads, sugar, paste, etc. But it doesn't hurt your skin.
I got one on **** but you can find it other places but that's probably the cheapest place. You can also grow your own. I have a lot less ingrown hairs now and it's removing the skin that's covering the ones that I had.