I got this puffer vest for the colder fall/winter days. I am pleasantly surprised, usually, Nelly does not like jackets and tends to do the awkward shuffle the first 15 minutes of the walk but with this one she didn’t. I wasn’t sure about the sizing before buying and got a small. For context, her back length is 20” long and the small fits perfectly. The loops by the straps help to pull in the loose jacket bits as well. Very happy with this purchase.