The Type F Equipment was developed by Ritsuko Akagi to address the Evangelion units' lack of mobility and armor strength, which had been significant issues in their battles against the Angels. Despite the increased weight due to additional armor, the newly developed A.T. Field propulsion device provided the Evangelion with enhanced maneuverability and defensive capabilities, making it far more effective in combat.
However, SEELE perceived the construction of the Type F—an exceptionally powerful configuration for what was supposed to be an experimental machine—as a potential sign of rebellion from NERV's Japanese headquarters. Consequently, SEELE requested modifications that limited the Evangelion's ability to wield firearms. The Type F's hands were redesigned to prevent it from holding large weapons, restricting its armament to a Progressive Dagger stored in the shoulder pylon. Despite these restrictions, NERV secretly produced a modification kit for the Type F that enabled it to use various large firearms, disguising the kit as an Evangelion transportation unit. This kit was deployed during the defense of NERV's Japanese headquarters.
The Type F armor was also designed to test advancements in A.T. Field generation technology. The aim was to enhance the Evangelion's defensive capabilities through artificial deflection of A.T. Fields, and to potentially enable flight—similar to Evangelion Mark.04A, which uses its A.T. Field for space travel. Although full flight capabilities were not achieved, the Type F allowed Evangelions to perform field-assisted jumps, covering significant distances and outmaneuvering lighter units, even with the added weight of the armor. To further improve its maneuverability, jump jets were integrated into the knee shields of the Type F.
During a clash with Evangelion Unit-0.0 Mutant, Shinji manifested a spherical A.T. Field centered on himself. He expanded this field to an enormous size, engulfing everything around him, including Unit-0.0. The field caused the air inside to lose pressure, akin to a piston being pulled from a cylinder. A bright white flash followed as the field expelled thousands of cubic meters of lake water in the shape of a bowl 1,200 meters high. The expelled water instantly froze, forming ice strong enough to initially support the weight of the Mutant, which only later began to crumble as the Mutant slid downward. This ice bowl absorbed the shock wave's energy, preventing it from causing massive damage to the city.
The results of this A.T. Field manifestation left NERV Japan's scientists in awe. They observed that the temperature at the field's center had dropped from 1,000º Celsius to -200ºC. There was speculation that the phenomenon involved Adiabatic cooling, but some data suggested manipulation of the particles’ center of mass. Additionally, the ice formed was unusually strong and resistant to melting. Maya and her team grew increasingly concerned about the unusual and potentially dangerous developments involving Unit-01.