Prevents biters from chewing on your infrastructure by making it invincible.
The entities to be affected are controlled by two settings, applying to either all entities of a specific type (eg electric-pole) or of a specific prototype (eg bit-electric-pole). The settings use a list of internal names, which can be found on the entity's page on the Factorio wiki. An entity that matches either list is made invincible. As a special case, with the large number of rail types added in 2.0/Space Age, an option to affect all rails is also included.
By default only affects newly-placed entities but can retroactively affect existing entities. This can take a couple seconds for very large worlds.
Example filters
To include all belts and the big electric pole, the type filter should be set to
transport-belt,underground-belt,splitter
and the name filter set to
big-electric-pole
Uninstalling
If uninstalled, entities will still be invincible. To avoid this uncheck all settings and set "Affect entities already placed" to remove invincibility.