When the time comes, it's easy to replace the fill in your dog's bed. This inner cushion is channeled to prevent clumping and shifting, a technique that keeps proper support throughout the bed. It is filled with high-loft polyester fiber to create an incredibly comfortable, mattress-like bed. The three sewn in chambers maintain balance and even distribution of comfort. Unique pass-through material allows moisture to drain from the bed in case of accidents or outdoor environments.