A cylinder lock includes a lock housing receiving a plug assembly that has a key hole, tumbler pieces having respective toothed parts, and a re-keying unit. Each of the first radio base stations reports to the second radio base station the transmission timing of frames to the first terminal, and the second radio base station synchronizes the transmission timing of transmitting frames to the second terminal with the reported transmission timing. The slider comprises two sliding rails that protrude from a bottom surface of the slider, extend from a leading end of the slider to a trailing end of the slider, parallel to and at a distance from each other, and have near the trailing end of the slider a rear edge that works as a sensor for detecting the defect of the magnetic disk.