The Commonwealth Armor gives you full status effect, struggle and critical hit resistance for X amount of turns, as well as has a Y% chance of gaining a charge point when hit by an attack.
If your survivor gets into struggle and red health during the enemy turn, your survivor will not take any additional damage from other attacks during that same turn.

Note: When the Commonwealth Armor is paired with similar functionalities such as Morgan's Leader Trait (Defensive Charge), the chances of getting charged from an attack are not summed up, instead they are rolled twice. This means that the survivor may get 2 charge points from a single enemy attack - one from the Commonwealth Armor and one from the Defensive charge.