Forerunner supply elevator
From Halopedia, the Halo wiki
The Forerunner Supply Elevator is a building in Halo Wars. It is a structure that can be captured and controlled. When it is controlled and an infantry unit is garrisoned inside, this building will perpetually create supplies for the player that commands it. It is a Forerunner structure that fulfills the function of a UNSC Supply Pad or the Covenant Warehouse. This can give the player a chance to replace the supply pad with something else, however if they then lose the structure they will be without a source of Supplies, but because attacks on their base are much more frequent then that on the Supply Elevators, there is less of a danger of this happening.