It arrived flat which was nice. Not as stiff as I had hoped and the bumps on the bottom that go into the carpet are not as long as I had hoped. I have a thicker carpet and I need to keep readjusting it because it slides---not much but enough where I need to keep shifting the mat. If I didn' t have such a thick carpet it probably would work fine.
This mat works pretty well. It allows my chair to move more smoothly over the carpet. However the plastic is soft enough that it will temporarily deform and create little "ruts" - and I'm not a big person (165 lbs.). These requiring a bit of a shove to slide out of.
It works but is very thin compatible to one it replaced the rollers on the desk chair sink thru it easily - so I will need to replace it with one that is of better quality