Head restraint means a device that limits rearward displacement of a seated occupant's head relative to the occupant's torso.
Height means, when used in reference to a head restraint, the distance from the H-point, measured parallel to the torso reference line defined by the three dimensional SAE Standard J826 JUL95 (incorporated by reference, see § 571.5 ) manikin, to a plane normal to the torso reference line.
Top of the head restraint means the point on the head restraint with the greatest height.
49 C.F.R. §571.202