Apparatus for sterile transfer of material between a container and an isolator, wherein the container has a container opening surrounded by a container flange and a container lid removable from the container flange for closing the container opening, wherein the isolator has a port opening surrounded by a port flange, a port door for closing the port opening and an actuating mechanism movable between a closed position and an open position for opening and closing the port door, wherein the container flange is detachably connectable to the port flange and the container lid is detachably connectable to the port door, and to one or more of the following safety devices (50, 52, 54): - a first safety device that blocks the actuating mechanism in the closed position and releases it when the port door rests against the container lid, - a second safety device that blocks the actuating mechanism in the closed position and releases it when the container flange is correctly connected to the port flange, - a third safety device that blocks the container flange connected to the port flange when the actuating mechanism leaves the closed position, and that prevents the two flanges (16, 22) from being released from each other as long as the port door is open, - a fourth safety device that blocks return of the actuating mechanism from the open position to the closed position when the port door is open, and - a fifth safety device, which blocks the actuating mechanism if the container flange is not correctly connected to the port flange between the release of the actuating mechanism by the second safety device and the blocking of the container flange by the third safety device, characterised in that at least one of the safety devices (50; 52; 54) comprises two magnetic fields (56, 58; 60, 62; 64, 66), which are movable relative to one another, in that at least one closed wall (68, 70) without a through-opening is arranged between the two magnetic elements (56, 58; 60, 62; 64, 66) and in that the magnetic elements (56, 58; 60, 62; 64, 66) attract or repel one another through the closed wall (68, 70) either in a blocking position or in a release position of the safety device (50; 52; 54). - a first safety device that blocks the actuating mechanism in the closed position and releases it when the port door rests against the container lid, - a second safety device that blocks the actuating mechanism in the closed position and releases it when the container flange is correctly connected to the port flange, - a third safety device that blocks the container flange connected to the port flange when the actuating mechanism leaves the closed position, and that prevents the two flanges (16, 22) from being released from each other as long as the port door is open, - a fourth safety device that blocks return of the actuating mechanism from the open position to the closed position when the port door is open, and - a fifth safety device, which blocks the actuating mechanism if the container flange is not correctly connected to the port flange between the release of the actuating mechanism by the second safety device and the blocking of the container flange by the third safety device, characterised in that at least one of the safety devices (50; 52; 54) comprises two magnetic fields (56, 58; 60, 62; 64, 66), which are movable relative to one another, in that at least one closed wall (68, 70) without a through-opening is arranged between the two magnetic elements (56, 58; 60, 62; 64, 66) and in that the magnetic elements (56, 58; 60, 62; 64, 66) attract or repel one another through the closed wall (68, 70) either in a blocking position or in a release position of the safety device (50; 52; 54).