Thank you so much to everyone who said that these do enlarge to fit bigger size heads, despite the negative reviews about size from other people who couldn't figure out how to use the product.
These headphones fit my 27 year old 6'1" male head, just as well as they fit my less than 5 month old daughter's head. We put them on her, and she started laughing and giggling (one of the first times she has ever done that). I extended them to their largest size, and they went right on my head (and my wife's head) just fine.
DO NOT LISTEN TO THE PEOPLE WHO SAID THEY DON'T FIT LARGER HEADS. These people simply did not know how to use the product.
Now, my daughter will be able to enjoy her first San Jose Sharks game, and it's the season opener, so it will be very loud!