A Friend Credit is a type of Bonus Credit that is green in color. Players can obtain one by having someone on their Friend Roster send them a Friend Voucher. Thus players can practically get unlimited Friend Credits because they can send them as many Friend Vouchers as possible, and then start their game over (Alternatively, they can just back up their save file to an SD card, send the Vouchers, and then restore the backed up file, completely restoring the Vouchers that were sent). These are needed to unlock extras in Metroid Prime 3: Corruption and Metroid Prime Trilogy, such as a majority of the Concept Gallery and everything in the Bonus Gallery. Fifteen are needed to unlock everything in one save file.