Hi! I have a Critter Nation cage since last year. The tenants are 2 to 3 female rats at the time. I have been using lightweight fleece to cover both pans since I bought the cage. Depending on the rat,mild chewing or rage chewing is involve hehe. I wash an sew munched pieces together and usually make months with my stash but lately, Clementine the Great is cutting around every single clip that secure the fleece on the pan. I try this week to secure only the front as I noticed they go under to have power naps and even bring the water bowl with them. The result is, of course, not very neat and I wonder if you all use fleece or if some of you simply don't cover the pans? Oh and the ladies don't bother too much using their litter box anymore, a corner of the plastic pan seems to have a new purpose now.