A closure (2) for closing an opening of a container (1) for storing and removing sterile or moisture-sensitive media has a closure cap (3), which can be connected to the container in a fluid-tight manner, and a piercable, self-closing septum (20), which closes at least one removal opening (7) in the closure cap (3) in a fluid-tight manner, wherein the closure (2) has a rotatably mounted protective cap (4) with a cutout (5). The cutout (5) is arranged off-centre in the protective cap (4) and the closure cap (3) has off centre a closure region (9) which is not impinged by the at least one removal opening (7) and is larger than the cutout (5) in the protective cap (4). The closure (2) has a latching mechanism, which is suitable for arranging the protective cap (4) in relation to the closure cap (3) in such a way that the cutout (5) in the protective cap (4) is aligned either in line with the or a removal opening (7) in the closure cap (3) or at a distance from the removal opening or openings (7). The closure (2) has at least one tamper-proof means of protection.