A disk brake piston system having a piston having a metallic outer wall surrounding a central axis, the outer wall being of a material and a thickness which that could be formed by deep drawing; a metallic front wall closing one end of the outer wall, the front wall including a curved area extending toward an interior of the piston, the front wall being of a material and having a thickness that could be formed by deep drawing; and a sleeve positioned at least partially within the piston and configured to interface with an interior side surface of the outer wall such that the sleeve and the piston are restrained from rotating relative to one another around an axis parallel to the central axis, the sleeve comprising a flat or curved internal surface, having a non-circular cross-section, wherein the sleeve comprises a polymeric material.