Abstract: This invention provides an improved aerodynamic disc comprising a central portion and a perimeter portion, the perimeter portion defining a central cavity situated within the central rim portion, in which upper and lower openings are connected by a threaded circular sidewall. The central portion of the disc contains a rotatably removable insert which is threadably engaged with the threaded circular sidewall of the central cavity. The insert comprises upper and lower circular surfaces which are connected by a threaded circular sidewall. The threading of the central cavity sidewall of the disc and the circular sidewall of the insert, are in male/female relationship to one another. Accordingly, by inserting and rotating the insert in the central cavity, the threads become engaged thereby locking the insert into the central cavity. Conversely, the insert may be rotated in the opposite direction, thereby removing it from the cavity.