i use aspen (was using carefresh but the 'allergic' response my ratties were having to aspen seemed to have stopped after taking a 9 month break from it) in all my rattie enclosures. we buy polar fleece, cut it up for hammocks and also lay a piece over the cage in the winter... that way they can pull it through the bars and use it for whatever they wish LOL

they are totally spoiled... i figure if i was a rattie... i'd be okay with living in my house - and so i'm pleased with our care.