MFFS Frequency Cards are used to link one or multiple MFFS Projectors to a MFFS Core. You obtain them by putting a Blank MFFS Card into a MFFS Generator Core's Frequency Card slot.
You must craft and write an MFFS Card for every single projector you wish to create, but you do not need cards for Forcefield Upgrades.
Once made, they are to be placed into a MFFS Projector's Frequency Card slot, allowing it to receive Force Power from the Generator Core it is linked up to by the card.
It is not possible to run MFFS Projectors without the usage of Frequency Cards.
When a Projector containing a Frequency card is destroyed, it drops the card as a blank card, thus resetting the card. The card is lost if it is left in a Forcefield Core when a MFDevice is used to recover the Forcefield Core.