Years ago, the local megastore had three or four different types,
but unfortunately they have stopped selling any of them here.
Astroturf doormats work great for the cat litter box area. They
work great for cat sleeping mats too, with some cover like a
towel, because they are breezy and therefore cool underneath.
Might have to get my next set online.

Funny, but they do not work well for doormats because exposure to
the sun degrades the plastic and the stems start falling off.
Inside, the plastic lasts forever without shedding. Apparently
they have not been using UV resistant plastic.

I think most of the ones I bought were the "Clean Machine".

Searching the Internet, I noticed they are being marketed as
"litter busters" now.

http://grassworxllc.net