This swim diaper is great to use since disposable swim diapers are so expensive. It is easy to get on and off with the side snaps as well. And realize that those people that complain that it doesn't work don't understand the purpose of a swim diaper. It will not keep the urine from leaking - it is purely to keep the solids from going into the pool. That is pretty much how all swim diapers work, or else you would have a 50 pound baby coming out of a pool! So just put the diaper on right before going into the water and switch it out for a regular diaper when you're done. The sizing off the product's label (don't follow amazon's sizing) is as follows: small is 10-18 pounds, medium is 18-22 pounds, large is 22-25 pounds.