Radio Controlled Movement sweep second hand quartz clock movement alrm clock movement WWVB ... Alarm Movement, step movement Specifications:Model NO.: DM7920 (WWVB) - Sweep Second HandSize(MM): 78x65x20Other Relative Models:DM7820 (WWVB) - Step MovementDM7810 ... DM7840(MSF) - Step Second HandDM7910 (JJY), DM7930 (DCF), DM7940(MSF) - Sweep Second HandFeatures:1. Frequency:40KHZ/60KHZ auto change(JJY),77 ...