Folks in the store tried to talk me into the more expensive matt saying that this one would ruin my carpet. It might do that over time but so far it has been GREAT and I am thrilled to have something so economical to work with.
These things are garbage -- not worth the price! The last about 15 - 18 months and then get brittle and crack and eventually fall apart! Staples ought to get rid of this line and offer something of better quality.
My last one lasted several years but cracked. This one feels better quality and is very easy to roll around on. I bought a second one for my Mom and she loves it (she's in her 80's and can't believe how easy it is to roll around on her office chair now).