Principle of Operation: At the beginning, green led light on the upper half, then flows to the lower half like sand. ... Principle of Operation:At the beginning, green led light on the upper half, then flows to the lower half like sand. The process will finish in a certain time....

The description of work principle: First, green lights are flashing at the top part, then go down like sands, and must be reach The description of work principle:First, green lights are flashing at the top part, then go down like sands, and must be reach at the bottom in a...