Our 13 lb. Jack Russell, Annie, has paralyzed back legs due to a spinal cord injury. She can now go to the places she used to go with us...hiking in the mountains (backpack), and for walks in the park (wheeled)...She is very content and really loves it, plus she gets a lot of attention because she looks so cute in it!  I was looking at cheaper one's, but opted for this one and am so glad I did. It's made very well, is very durable, and very comfortable for Annie, as well as for us when used as a backpack. The size is perfect too!