the smaller size is perfect for my aussiedoodle with room to move. Fits nicely under the sleeping bag. We used it today at a restaurant and its just nice to have somewhere soft to lie on, mind you, it is thin, but it just gives a nice layer between the cold hard floor and the dog. Nice rubber-ish type feeling material on the bottom which should be good for rough or damp ground. Havent camped or hiked with it yet, but she really likes it with the sleeping bag and so do i.