Camelbak Podium® Flow™ Belt 21oz Camelflage/Brown Seal
The minimalist MTB solution for cargo and hydration.
I bought these for my 8 and 10 year old boys who are both average size, 55-60 lbs. The packs are really adjustable around the waist so they fit them fine. My boys also have the kids Camelbak Mule but both kids much prefer the waist packs. Say they're more comfortable.