Coarse Critter’s Comfort animal substrate/ bedding. Critter's Comfort can be used as substrate or bedding in a reptile, frog, insect/ invertebrate, bird, rabbit, guinea pig, mouse, rat or ferret enclosure. It is made from 100% natural, renewable resources and is perfect for use in many different conditions. Designed to eliminate odors and help keep your animals warm and comfortable. Perfect for use in humid environments.