Mark Ryden USA Official Store | EXPANDER - Laptop Backpack – MARK RYDEN USA Official Store
I found a Kritzkrieg (ooohhhhhhhh) but didn't have any backpack slots open for it. No worries - an expander is 99 cents, I'll buy one... - 1 ITEMS BACKPACK EXPANDER REMOVE $0.99
Pacmo
Backpack Expander - Official TF2 Wiki | Official Team Fortress Wiki
Expander Chair Storage Bag - by Front Runner – Otzi Adventure Gear