Advanced Retrofits are upgrade cards played just like regular upgrades however they are played on the ship face down, rather than face up. These do not need to be shown to your opponent until the modification is used. For example, if a bonus given increases attack dice, the retrofit is revealed when making an attack. There are other cards that may cause you to reveal one of these upgrades at a time of the opponents choosing rather than of your choosing. Ships may have up to two upgrades of this type unless the retrofit changes the ship class.