An item drop for the mech that gives increased x by x space in mech inventory (the place where you put guns armor and equip).
example: Hopper: gives an increased 3x2 squares in a part. uses 1x1 space in part.
This means you have to use one of your drops in order to get increased capabilities later on.

If there is a plan to allow us buying/earning different mechs i think this equipment would be unnecessary. But if not, its a great idea.