Sarbar is correct--support structure is needed. Even with a 4-5 pound pack, the straps are going to cut into the kid's shoulders and hurt if there isn't something to transfer the weight to the hip belt. I found this out with my 5 and 7-year old grandkids. Load lifters are also excellent to prevent the straps from cutting into the shoulders. I just wish the manufacturers wouldn't make the rest of the pack so darned heavy. The REI Comet and Deuter Fox both consist of about 1 lb. of suspension; the rest is really heavy-weight nylon plus lots of unnecessary gewgaws. As I mentioned earlier, if you could put the MLD Kid's Prophet onto the suspension of an REI Comet or Deuter Fox, you'd have a great kid's pack weighing about 1.5 lbs.

I looked seriously at the MLD Kids' Prophet--even posted some queries about it--and decided against it. It's completely frameless--just a rucksack with no suspension and all the weight will be on the kid's shoulders. Even with 4-5 lbs, that's too much for my grandkids. It might be fine for older kids but probably not for kids under about 10-12 (varying widely with size and strength of child, obviously!).

I'm investigating the Gossamer Gear Mariposa in small (which will also fit kids--12" to 16" torso--and is on sale) and the packs are due to arrive Wednesday. I will try them on the grandkids (now 6 and 8) the following weekend, and if they don't work I'll send them back. If they do work, they will be put away for next Christmas. This pack is unfortunately a bit larger capacity than the Miniposa mentioned above. The Miniposa is being re-designed and the Mariposa is being discontinued.