I have a small and a medium one. I had a few problems with wicking (wetness getting on the cotton outer of the diaper) with the small one so didn't use it too much. I got the medium one to use as a swim diaper. It worked fine for that. I find the rise to be too low to fit over some of dds diapers, she has a pretty long rise though. It works with a very trim fitting diaper in it, like a trifolded infant CPF, or just a Joey Bunz. But I make sure I check her frequently and change her as soon as she wets. The Bummis SWW have a little longer rise, so they fit dd better.