Kaytee works. I've also used Alphapet aspen(from Walmart) and that works too. I'm now using American Excelsior right now which my snakes seem to love. I pretty much just get whatever I can find for a good price as I do monthly changing and it adds up fast. I found a source where I can get the 7.5 cu ft bags of American Excelsior for $25 which works out great, it's just a bit of a drive to pick em up. Just make sure whatever you buy, its pure aspen and not a mix or something.