This Heavy Duty Soundproof, Fully Mortised Automatic Door Bottom will provide an excellent door threshold seal. needed to retain your door's sound rating. The aluminum casing is fitted with a self-extinguishing and oil-resistant solid neoprene insert which serves as its primary seal. Solid Neoprene has high sound control properties and is very durable. It will hold up longer over the years and should be used when applied to high-frequency traffic or rough floor surfaces, such as concrete. Additionally, the interior of the aluminum anodized casing is filled with anti-squeak rubber for extra protection and to ensure smooth operation. This product is designed to be fully mortised into a wooden door. It is great for designer doors and high-end, luxury condos since the appearance of the door is not altered. It is non-handed and can be applied directly over the floor surface or above a doorway saddle, though a saddle is recommended for higher sound control (A saddle is highly recommended also when the door bottom is sealed onto the carpet). Available in aluminum mill finish and standard stock sizes. Installation instructions and screws were provided.