Fantastic durable bed. The bed has a zipper liner for the outside cover, brass zipper so high quality. The inside liner also has a zipper which is a good thing. Reason being is that even though this is a 'small' its rather big and tall, but mostly very puffy. Its puffy for that they really gave you your money's worth with the fill inside this bed. The fill is some sort of wool / hair, nothing synthetic from what I can see. I ended up removing a trash bag full of this hair filler to reduce the puffiness of the bed. I put the extra fill in the attic so I can replace over time and freshen up the bed as it ages. I highly recommend this bed.