Recommendations on a good chairmat

[PeterB]

I've asked about this here before... I seem to be having crappy luck with these. They always seem to last about a year or two, then start breaking. I could go through the hassle of returning under warranty, but it doesn't seem worth it.

Last time I asked here, I was told that Costco has good ones... looking there, I see a good number of different types though, and not sure what to get. I need approx. 36" x 48", with a 18" wide lip, for low-pile carpet.

TiA