What kind of litter do you recommend we use?

We recommend that you use a litter which is made from recycled paper, such as Carefresh White Small Pet Bedding, or So Phresh.  Avoid wood shavings, as they do not absorb odor and urine as well, and some (pine) might be harmful.  Avoid any liter with baking soda or other additives, as your rat may ingest it.