Sinkhole Backpack

The Sinkhole Backpack is a medium backpack made by Doomsday. It is actually a modified version of CSP-68M Backpack manufactured by Clark Defense Systems.

In-game description
"Stop lugging all your loot by hand. The Sinkhole backpack gives you plenty of space to store everything you need, while leaving your hands free for whatever mischief you have in mind."