The heaviest of heavy armor, hydraulic plate is built superfically like full plate, covering the entire body in metal. However, it significentally bulks the user up, for the metal plates are so thick no man could concievably move within it. Therefore between the outer armor and the user inside is a complex rubbery layer of fluid bladders which shift and move as the user does, adding extra pressure on certain joints to allow the otherwise immobile joint motion, and allow the user to move, hence the hydraulics in hydraulic plate. Such movement is much more clunky than normal walking, and so the penalties for this armor are much more severe.