The invention relates to a device (100) for providing a crossover point between a first region (1) and a second region (2) hermetically delimited from the first region (1) by means of a wall (10), wherein the device comprises: - a lock chamber (12), which can be inserted into an opening (11) provided in the wall and which has a first opening (13) forming a crossover point between the first region and the lock chamber and which has a second opening (14) forming a crossover point between the second region and the lock chamber; - at least one peripherally circulating element (15), which has at least one passage opening (15.1; 19.1; 15.2; 19.2) and can be moved in relation to the first and the second opening of the lock chamber so that at least a first state, in which the at least one passage opening is substantially aligned with the first opening of the lock chamber and enables access from the first region into the lock chamber and the peripherally circulating element covers the second opening of the lock chamber substantially completely, and a second state, in which the at least one passage opening is substantially aligned with the second opening of the lock chamber and enables access from the second region into the lock chamber and the peripherally circulating element covers the first opening of the lock chamber substantially completely, can be selectively effected.