Suggestion: Backpack Expander at 2–2.5 keys - backpack.tf
Backpack Expander - Official TF2 Wiki | Official Team Fortress Wiki
Golden Wolf GB00458 Expander Travel Backpack - ETCT
100L Large Capacity Travel Climbing Bag Tactical Military Expander Backpack Canvas Bucket Shoulder Sports Army Rucksack,2,One Size: Buy Online at Best Price in UAE - Amazon.ae