Can be made into double-sided clock. Using ac 220v 22v and 50hz 5hz, or 110v 11v and 60hz 6hz . With backup dc power supply, storage battery full charged going for more than 2 hours. Accuracy of travel time: day difference 0.2s (in spring and autumn)day difference 0.2s (in winter and summer). Working environment temperature: -40 to 50 Installation: wall-mounted (only for one side), double suspenders, bilateral support, or according to customer requirements. Can be added the following functions 1led spotlights luminous 2timekeeping 3adding rs485/422 serial communication function 4adding rs232 serial communication function 5built-in 485 repeater / splitter 6gps time synchronization 7long-wave timing signal synchronization 8infrared mobile master clock synchronizes time 9rf mobile master clock synchronizes time 10infrared clock adjusted device adjusts time. 11: rf clock adjusted device adjusts time. 12infrared mobile master clock synchronizes time and automatically records the synchronization time. 13: rf mobile master clock synchronizes time and automatically records the synchronization time. Diameter:500-1000mm