3-inch hour, minute, and second synchronous clock

1. Time synchronization methods: NTP, WiFi 2.4G or 5G, LTE-4G, LoRa wireless communication, etc. (select one); 2. Clock accuracy: Operating time accuracy: 20ms; 3. Power supply methods: AC220V, POE, DC6V (select one); 4. Timekeeping method: Temperature-compensated crystal oscillator timekeeping, RTC annual error less than 1 minute without time source; 5. Display method: Hours, minutes, seconds; single-sided display / double-sided display; 6. Management methods: Operating status, time synchronization status, communication status, power on/off, self-reset, countdown, time zone, brightness, time synchronization cycle, network parameters; 7. Equipped with identity authentication function; 8. Fully domestically designed, with MCU, network communication chips, and components all domestically produced; 9. Hour, minute, and second digit size: 3 inches; 10. Display colors: Red, white, and green; 11. Frame colors: Brushed metal, milky white, and matte black; 12. Frame materials: Matte aluminum alloy frame, stainless steel frame, acrylic panel; 13. Installation methods: Ceiling mount, wall mount.