An automatic swing arm, also known as a swing arm operator or swing gate opener, is a device used to automate the opening and closing of swing gates. It is designed to attach to the gate and control its movement, allowing for convenient and automated access.

The swing arm operator consists of a motorized arm or actuator that is mounted on a post or pillar beside the gate. The arm extends and retracts to open and close the gate in a swinging motion. The arm is typically attached to the gate leaf, either directly or via a linkage mechanism, and moves it inwards or outwards to provide an opening or closure.