This thing slides all over carpet like crazy. If you step on this mat without a chair on it you might very likely lose your balance and fall on the floor. Even with the chair on the mat it will still slide and is very annoying.
The grip points are bevelled and therefore do not maintain adequate grip on the floor. As the chair moves around so does the mat. Also the plastic used could be a bit thicker. Returned this mat and bought a different brand which works better.