One tip....never by clumping cat litter...rabbits tend to eat their litter and it can clog them up and kill them!I just use normal wood shavings, some rumors go around about how dust can effect the rabbit or w/e but it never has happened and I've been using these ever since day 1. Around here the cost for a HUGE I mean HUGE vaccum packed bag of wood shavings(no pine or ceder,dangerous) for about $3.00 a 15lb bag of pellets for $5 and a bale of hay for $4! Dirt cheap! While not even a 5lb bag at a petstore is $7! Anywayz good luck litter hunting!