First off, I had to consider this purchase due to the expense as well as having to wait to receive a response on sizing. Plus I was disappointed that a $5.99 shipping charge was incurred even if it was shipped to the store. I purchased for an 11 lb chiwahawah so selected the corresponding size of Small for up to 20 pounds. It was so tiny- the hook & loop velcro straps looked like i sewed them- and would barely reach around her tummy and certainly not worth nearly $40 with s/h & taxes. Returned to store for refund upon receipt of item- of course minus the $5.99 Most disappointing. I could not recommend this brand if they are all sized like this.