My 2.5 year old grandson is FAST and I'm not as fast as I used to be.  We use this when going for walks around my neighborhood. He's completely unaware that he's on a tether because we usually hold hands while walking; the tether is an extra safety measure that I keep around my wrist..  I have rheumatoid arthritis and if he would dart into the road, I worry that I wouldn't be able to run to him quickly enough. I He loves it because it's a "big boy" backpack like his elementary school aged cousins have.  He puts his water bottle in the mesh pouch and I put my phone and house key in the zippered section and we're good to go!