A part that would allow a ship to split into two or more pieces. For example lets say i had a brawler type vessel thats made to get up close and personal but i have a series of interlinked cargo bays that could be detatched when entering a battle and reattatched for salvage operations or shipping.
perhaps a main ship with a detatchable railgun that can pivot and fire but is seperate from the main body of the craft to avoid chain reactions destroying the whole vessel.