Force fields are special shields and barriers used to provide protection.
After most of the Bug Jar's population turned EVO, the city was enclosed in a force field to isolate the EVOs from the rest of the world. The shield acts as a one-way barrier, allowing outside entry but preventing those inside from escaping. However, a massive explosion can temporarily create an opening in the shield.
The force field is generated by a shield regulator located in the sewers below the Bug Jar. The shield regulator occasionally malfunctions and requires maintenance.
The molecular destabilizer was secured inside a force field that could destroy anything made of organic matter. Quarry was immune to the force field because of his inorganic body.
Using the Block Party build, Rex can generate two light blue shields capable of blocking energy-based and physical attacks. However, his force fields can shatter very easily.