I have a large 4 year old that can wear a size 6.  These pajamas help to keep her cool in the summer months,  The material is stretchy so you don't have to worry about the fitting so much.  The material is soft and stretchy and not too thin such that it will fall apart or anything.  It's well made and the design has not washed off after multiple washings.  The longer shorts make it not ride up.

This feels very comfy.  Trust me.  My very picky daughter is the first to complain about anything not being comfortable.