This invention pertains to an article designed to warm and comfort the feet. In accordance with the invention provision is made for the rotary feedthrough to have a rotary device for actively rotating the second line connection relative to the first line connection. For each stage a stall signal, delayed with respect to the stall signal of a downstream stage, is generated and used to select whether the pipeline stage in question is triggered. The invention also relates to an electrical system and a method for limiting an electrical current in an electrical conductor of an electrical installation. The reservation confirmation whether that the QoS reservation was successful. According to the apparatus, even if it takes a relatively long time to replace the wafer on the wafer holder used inside the reduced pressure space, by performing the wafer exchange operation and a predetermined operation using the stage on which the wafer holder holding the wafer is mounted concurrently, the influence that the wafer exchange time has on the throughput can be suppressed.