I ordered the Thirsties medium wet bag for my son's school backpack. We are very fortunate that his preschool will let him wear his cloth diapers, but I needed another wet bag to send to school. I ordered the bag because of the size and I was pleasantly surprised with how amazing it is. First, it folds up super small and will easily fit in the most full bag when it is empty. You can keep it tucked in your diaper bag or purse for emergencies, or even put it in your pocket to be discreet if necessary. It is a single piece of PUL, not lined on the outside with other fabric like so many other wet bags on the market. This makes it small, compact and easy to wash. The added strap, which on most other wet bags is for carrying or hanging, is made with the snaps on in such a way that it can be used to secure the bag folded up super small. I have 3 or 4 wet bags from other brands, but this is by far my favorite.