Materials, equipment and documents can be transported in the Cleanroom materials, equipment and documents can be transported without employees having to enter and exit. A material airlock functions thanks to mutually interlocked doors. As only one door can be opened at a time, the pressure difference between the rooms is maintained. The air in the material lock is “purged”, i.e. filtered and exchanged, during the material transfer. This removes airborne particles and minimizes contamination.