Earlier I reviewed the Thirsties Duo-Wrap cover. Here's a picture of Second Son in the size two.
I think he's still shy of 17 pounds in this picture (taken yesterday), and the size two fits perfectly with the aplix tabs stacked like this. I know they will work at least up to 30 pounds because Second Daughter was wearing them until a few weeks ago.
Doesn't he look delightfully squishy?