A medium duty, automatic door bottom seal which can be face-fixed or semi-rebated to the bottom edge of single action doors. It operates automatically by a spring loaded mechanism which lifts the seal clear of the floor as soon as the door is opened. The seal is fixed to the face of the door bottom using the ferrules and mounting screws provided. When the seal is to be semi-rebated, the seal is mounted into a 35mm deep x 14mm wide machined groove in the side of the door where the seal is to be positioned. The seal operates automatically by pressure against the door jamb on its adjustable strike button. The seal contains a high efficiency mechanism to assist with the closing force requirements detailed in AS1428/1 (Design for Access and Mobility). Aesthetic, nylon push-fit end plates ensure longevity of the seal mechanism.