A Backpack SDU (Storage Deck Upgrade) is an upgrade which you gain by completing Claptrap Rescue Missions in the game. By applying a Backpack SDU, you gain three extra inventory slots in your backpack. There are 10 obtainable Backpack SDU's which can be gotten in the first playthrough, allowing for an extra 30 inventory slots, giving your backpack a total of 42 inventory slots. There are 5 obtainable Backpack SDU's which can be gotten inthe second playthrough, updating the total of inventory slots to 57. And in The Zombie Island of Dr. Ned downloadable content pack, there are two more Backpack SDU's which can be found, putting the maximum inventory slots to 63.
|Playthrough One||In The Zombie Island of Dr. Ned|
|six||In Playthrough Two|