A threading unit for threading a thread through holes of a sheet-like flat member, including an upper block and a lower block mating with each other and each having formed therein a discontinuous vessel having apertures open on the respective mating surfaces. In an embodiment, the scan chain latch circuit comprises a first latch for holding one data value, a second latch for holding another data value, and a multiplexor. The lens module is axially movably received in the lens holder. The plug-in adapter includes electrodes and an adapter connector that is configured to plug into the base connector. The device includes a microphone that senses an audio signal generated by the medical device when the medical device alarms.