Size medium - big enough for two cats or smallish dog. Diameter of exterior is 27.6 inches, and inside diameter is 17.7 inches - Super cozy and mimics their mother's fur. - Quality, breathable materials for hours of sleep. - Washing machine and dryer friendly. I bought this recently, but neither of my cats use it - one of them maybe slept on three times. Hopefully, your pet will get enjoyment out of it. Paid $81, yours for only $40 Link to Brooklyn's website to view the product information: https://thebrooklyn.net/products/brooklyn%C2%AE-deep-sleep-cat-bed?variant=37834287284386