Right-click the Filter Screen with an empty hand to change direction it faces to.
Put a container block on the Filter Screen, and put some items into that container block, then the filter will stop any item entities except entities of items in the container.
The container on the Filter Screen acts as a whitelist.
If multiple Filter Screens stack vertically, they will use the nearest container which is above them as whitelist.
A simple filter. The types of items being able to pass is decided by the containers above the Filter Screen
Filter Screen only stops drop item entities, other types of entities can go through it easily.