Methods, systems, and apparatus, including computer program products, for a rental service through a computer network. The JTAG interface receives control information indicating a first amount to advance a synchronous data strobe associated with a first data group and a second amount to delay a data bit signal associated with a second data group. The coating forms at least one geometric deviation from the cylindrical inner contour of the hub bores. The control center transmits information of the available locker to the user terminal.