Abstract: The air lock includes a frame, a passage port defined by the frame, a plurality of side by side tabs supported in a rotating manner by the frame and extending through the passage port as well as kinematic connections between the tabs to ensure simultaneous and synchronized movement of each of said tabs between a closed position wherein all the tabs are essentially coplanar and close the passage port and an open position rotated by approximately 90.degree. in relation to the closed position. The air lock is characterized in that each tab is supported by the frame by at least one supporting plate separate from the frame and inserted in a pair of tracks formed in the frame and in that the kinematic connections are housed in a space made in the frame and enclosed by the tab supporting plates.