Stabilizers are a non-essential part of NEXT seen exclusively in Armored Core 4 and Armored Core: For Answer.
Stabilizers are small add-ons that can be put on the frame parts of an AC. They are used to offset center of gravity of an AC unit for better control; because AC's are not always symmetrical, stabilizers are almost always needed on a design. Stabilizers have low weight and energy drain, but still hamper a design's stability, energy supply, turning speed, and so on, depending on how many are equipped.
Boost speed and turning are affected by the center of gravity, so a back-heavy AC will be able to move forward faster, and an AC that is heavy on the left will boost and turn to the left faster, but boost and turn slowly to the right. Because of this, close-range designs will forgo moving backwards and put a number of powerful stabilizers on their back so they can close in quickly; designs that use weapons that are dropped quickly will equip stabilizers so the AC is centered when the part is dropped.
Stabilizers can be manually equipped to an AC. If a player doesn't want to manually equip his/her AC with stabilizers, they can choose an option that automatically adds stabilizers to the AC.