I've carried it a few times and used the shoulder strap for a short time, but I don't remember using the Boston bag. I'm selling it because it's a waste not to use it. It's designed to be placed on top of a suitcase. When used as a shoulder bag, pockets are created on both sides. The Boston bag and shoulder bag are not detachable and are integrated. (The Boston bag folds up and fits inside the shoulder bag) Non-smoker, no pets. For those who don't mind minor details.