In the Filter's GUI, which can be opened by pressing right click while holding the filter in hand, the player can specify which items can be visible.
The player can choose to let the filter be damage, NBT and oredict sensitive. It is also possible to use a mod filter.
The Filter can be set in a whitelist or blacklist mode, too.
Icon and name
The player can also configure an icon and name for the Filter.
As soon as the Filter has an icon specified, it will appear as a tab in the Grid. Then, open the tab to see the filtered items.
Clearing the filter
Use SHIFT + right click in your inventory while holding the Filter to clear it.
Putting the filter in filter slots
The player can also put the Filter, along with the filtered items in it, in the filter slots of the various Refined Storage devices. That way, you have more space to declare extra filtered items.
Note that the extra configuration options like comparing on NBT, damage, oredict or mod filter are ignored from the Filter itself. It will only respect the configuration options of the device the Filter is put in.