Our Sealing Systems for Doors is a heavy duty door accessory that works to seal the gap between the door and the door jamb along the sides, top and bottom of the door. Gaps in sound barriers are a major problem because sound travel through any opening with very little loss. Imperfect alignment is a common cause of gaps even in newly installed door. This adjustable door stop is acoustically rated to achieve an STC rating of 35-45 on a commercial door. Automatic Door bottoms function with a mechanism that causes the insert seal to activate on the hinge side first. It prevents the seal from dragging along the floor or threshold while the door is being closed to avoid door hang-up or closing delay.