Linear Gauges are usually used to demonstrate a single value of a measurement made at an exact point in time, using as less elements as possible to make the chart more clear to understand.
This chart shows the population statistics for 10 largest cities in the world. There are two gauges for one city: a gauge of LED pointer type demonstrates the rounded value and the bar pointer shows the exact value of the population in this town. The bar pointers can be selected. When you hover any of the pointers related to a town, the corresponding axis label text becomes bold, and the tooltip shows up. Each tooltip contains the information about corresponding town, showing the town name and the amount of people living there.