It is supposedly waterproof, so when the cat barfs on the rug or the grandkids spill on it (under the dining room table), I can clean the carpet with my little green machine and not worry about wrecking the wood floor beneath it. 

That remains to be seen, but I do know that it was easy to trim to fit under the rug, and I like its low profile so the dining room chairs don't noticeably sink into the carpet.