I have this nice dark grey FLOR carpet that was given to me when the Stanford d.school was getting rid of some things. I brought it home, but my roommates didn't like the color, so I'm giving it way. There are 20 carpet squares that are 17.9 inches on each side. You buy stickers from FLOR and attach the squares together in any configuration you like! Very flexible.

It looks darker in these photos than it actually is. It's NOT black. It's a stylish dark grey.