An internal frame mounted on adjustable elastomer shock absorbers on all eight corners. These revolutionary shocks are designed to control the effects of shock and vibration on three axes. The "sway" space around the internal frame provides natural air conditioning -- very important for delicate equipment. They are half the weight of the old wooden cases. - includes rear rails, front and rear lid - adjustable elastomer shock technology - precise level of shock absorption for any load - molded handles provide an easy and secure grasping point - mounting hardware in the racks is easy with the provided hardware