The Inogen One G4 system includes a carry strap to carry the concentrator over your shoulder. During longer walks, this might get uncomfortable. With this sporty backpack you carry the G4 safely on your back. Moreover, it gives you more storage space for your G4 accessories and personal belongings.Thanks to the adjustable chest and waist straps you can fit the backpack to your body perfectly. Don't need them? They're easy to remove so they don't get in your way.