US Patent 10463099 Protective helmet with multiple energy management liners

A helmet for rotational energy management can include an outer energy management layer comprising an outer surface and an inner surface opposite the outer surface. The inner surface can comprise a first slidable finish comprising a first glaze comprising a thickness less than or equal to 2 millimeters (mm). An inner energy management layer can be disposed within the outer energy management layer and further comprise an outer surface oriented towards the outer energy management layer and an inner surface opposite the outer surface. The outer surface can comprise a second slidable finish that directly contacts the first slidable finish. The second slidable finish can comprise a second glaze comprising a thickness less than or equal to 2 mm. A space between the first slidable finish and the second slidable finish can be devoid of a lubricant and devoid of any interstitial slip layer.