Abstract: A helmet comprised of a hard outer shell, a compressible liner in contact with an inner surface of the hard outer shell, and a comfort liner in contact with an inner surface of the compressible liner. The damping hole is defined longitudinally along a longitudinal axis through the hard outer shell, the compressible liner, and the comfort liner. The helmet also includes a pendulum damping system disposed in the damping hole and extending longitudinally from the outer shell to the comfort liner. The pendulum damping system has a pendulum mass that is laterally displaceable within the damping hole.