Orion does. From Rockport's website:"After precise registration and sealing of the outer carbon fiber components to the aluminum housing, the cavity between the aluminum housing and carbon fiber outer shell is completely filled with over 115 pounds of our proprietary, high hysteresis, high mass, structural damping compound. Once cured, this damping core intimately bonds the aluminum housing and carbon fiber shell together, consolidating it into a single, massively stiff, highly damped structure."