I love this, my dog doesn't, but it really does slow him down and makes it more manageable to walk him. He's a terrier pom mix, pom size and tail but terrier body and head. The small fits him really well, the straps are cinched to as small as they go which will work out fine if he gains weight. I did have to sew the stomach strap to make it shorter and fit better - he has a tapered body - but that took all of 3 minutes. I took someone's advice and put a couple of ounces of cream of wheat in waterproof baggies and positioned them in the side pockets near the shoulders, it adds a little bit of weight without hurting his back. I don't keep anything else in the pockets, it has a place for a baggie dispenser but frankly it's too small to make it easy to use without jerking him around. It has a chest cushion to keep the straps in place without digging in and another strap goes under his stomach. There's mesh sewn in to the top where the handle is so he still gets plenty wet when it rains but it also keeps him from overheating. I've used the handle to get his attention if something startles him and he starts barking uncontrollably but with only a strap under the stomach it's definitely not to be used to pick up the dog. When it's time to go for a walk he'll hem and haw about coming close enough to put it on him but he knows we won't go out until he has it on. When I first got it we worked up to wearing it whenever we went out. Now on the few times I've been in a hurry and didn't bother he spends the whole walk acting like Pinkie Pie on a sugar bender so it's very worth it to put it on him each time.