Really well-made product. Not too bulky and it's designed so that the pack doesn't flop around when my dog is running about. I got the size medium for my German Shepherd x Border Collie and it fits perfectly. Really like that you can use the harness on it's own without the pack, which is useful for day hikes scrambling over rocks and I think will also be handy as my dog ages so I can get him in and out of the car. I also have the Ruffwear Beacon light which I have attached to the pack too.