I bought this for each of my sons who were 2 and 3 at the time; they used their bags throughout preschool. For my youngest, now 4, I have a tough time fitting in extra clothes with his lunch and folder. I have to buy a bigger bag at least for my older son who is going into K this year. I may have to get my 4 year old a bigger bag as well.
I purchased this pack for my 4 year old for pre-school this year. It is the perfect size for her. It holds her snack bag and folder and a light jacket or sweater. the material is very durable, and I think we will get great use out of it. My daughter loves it because it resembles the older kids and she feels like such a big girl!
I bought the Original Jr Backpack last year for my preschooler. He's still using it this year for kindergarten and it looks barely warn. With 2 younger children, we plan on being able to use this backpack for many years to come. The only thing it lacks is an outside pocket for a water bottle.
I got my full size one in middle school and after high school, college, and lots of backpacking it is still going strong accept a strap that got chewed by the dog and I replaced. I got myself a messenger bag to use as a briefcase and love it too.
I ordered a red one for my son to start preschool and he is still using it this year for 1st grade. I am back for a pink one for my daughter for preschool and plan to get the bigger ones when they need them. These are plenty big enough for everything they need and the kids love them. I tell everyone I can about these as in the long run it is so much cheaper to get these then the regular store ones that you need to replace at least every year if not more often.