The Importer imports items or fluids from an inventory in front of the block and inserts it in the storage system (if there is space).
By default, it will import all accessible slots (place the Importer on the correct side, where the slot or fluid tank is reachable) but the player can use the whitelist or blacklist as well.
Whitelist and blacklist
There is also a whitelist and blacklist option to only allow or forbid some items from entering the storage system.
The whitelist or blacklist can be configured to be NBT, damage and oredict sensitive.