I have equimats in mine, the green locking ones. I like them as they are light enough for me to lift and sweep underneath. Ordered online and they were delivered no hassle . I have some of the 6 x 4 cow mats outside and they weigh a ton !
Mats I bought back in 2000 were very good but when I bought some more from the same supplier in 2011 they showed signs of wear literally in a couple of weeks, even the replacements they supplied did the same. In the end I got my money back and fitted Kraiburg KN mats (well a man came out and did it for me), more expensive than I'd wanted to pay but well worth it in the long run.
Quick caveat - you need well draining stables for rubber mats to work, otherwise the pee just pools (and stinks!!) under them. I can't have them for that reason, but instead I have flax or similar in a compacted base under straw topping, and just muck out the straw layer every day. Sorry, not what you asked I know but everyone seems to be jumping on the rubber mats bandwagon these days