I bought the extra large for my 60 pound fur niece and she's got plenty of room to stretch out. Bottom of bed has grips so it doesn't slide around and the bed is also quite heavy to lift, so it doesn't move. It was easy to put together and the foam expended quickly with no smell. The cover is a good, thick weight and not flimsy. The foam is holding up beautifully - no body outline indentations, which is surprising as she spends a lot of time in it now with all her toys. The bed was a bit pricey but is proving to be worth it.