The digital secondary clock, also named digital display secondary clock, adopts LED nixie tubes or dot matrix display numbers to display time information, and can be classified into calendar digital secondary clock with date display and no-calendar digital secondary clock by display mode. In addition, the digital secondary clock can display countdown, temperature, humidity and other required short contents besides calendar and time, has the advantages of high display precision (correct to one second), longer range of visibility (display distance), diversified and optional colors in display part and distinct and clear display, and can generate black screen in faults, thereby not misleading users. It also has the defects that the display is not direct-viewing enough (needing mental arithmetic sometimes), complicated structure, easy generation of chromatic aberration, unevenness display brightness, relatively shorter service life than that of the pointer type secondary clock; the digital secondary clock includes the single-side display and two-side display. 
There are some digital secondary clocks formed once by injection molding in our company, for example, 4-inch nixie tube: the secondary clock in “Hour: Minute” is in the specification of 53cm (L)*16cm (H)*4cm (T); 5-inch nixie tube: the secondary clock in “Hour: Minute” is in the specification of 67cm (L)*20cm (H)*6cm (T). Because of elegant, beautiful and attractive streamline casing and circular-arc edges, the digital secondary clock is especially suitable for being installed in airports, hospitals, high-grade office buildings, government offices and the like. 
Connotation of digital secondary clock model: