Double action door hinges are characterized by a spring-based mechanism that allows the door to be opened in both directions, swinging freely without the need for a handle or knob. The key components include the leaves (attached to the door and frame), pin (connecting the leaves), and spring (providing the swinging motion). Double action hinges are commonly used in high-traffic areas, such as entrances to commercial buildings and public spaces, where ease of access and quick passage are required.