A transfer device is a Space Pirate energy-distribution device capable of transferring enormous amounts of powerful energy between planets. This energy was created from a combination of a Liquid Resource from Excelcion and power cells from Bion. They use it in Metroid Prime: Federation Force to power the cloak that conceals the Doomseye. There is one transfer device on each of the three planets in the Bermuda System: Excelcion, Bion and Talvania.
Their existence is first discovered prior to M19: Incursion, after intercepted Pirate messages were decrypted. Initially, the Galactic Federation assumed there was only one device, and its destruction would expose the Doomseye. However, the Doomseye remains undetected after its destruction. Further decryption of the Pirate messages gradually reveals that each planet had a transfer device. The Federation Force is tasked with destroying the last two in M20: Insurrection and M21: The Core.
To destroy each transfer device, the Federation Force must target four nodes on the sides of the device's shaft with charged shots. Every device has a ring that slides up and down the device, so the Force must time their shots carefully. The mechanic of destroying a transfer device is similar to the launch of Recovery Pods in M08: Dustoff. The transfer devices are heavily guarded by Pirate forces, and gradually become harder to destroy. The Excelcion device is easiest to destroy, as it has minimal guarding and no extra protection. By contrast, the transfer device on Bion is more difficult to destroy. In addition to the ring, the nodes will also slide up and down the device, and underneath shielding where they can only be seen through a slit, and are not able to be destroyed. Also, Space Pirates consistently spawn to distract the Force. Talvania features the hardest device to destroy. It is guarded by Armored Bots, and infinitely spawning ground-based and Flying Pirates. This becomes very difficult if there are not enough Repair Capsules equipped, as the Mainframe is fought beforehand and there is no chance for the Force to repair their Mechs before they destroy the transfer device.
Once all four transfer devices have been destroyed, the Doomseye is exposed. This ship is then destroyed in the final mission, M22: Convergence.