A scale range specifies the zoom level at which a particular style is applied to the display of your data. When the zoom level of Infrastructure Studio or the Viewer is within the specified scale range, Infrastructure Studio redraws the layer as specified by the style associated with the scale range.
The style is applied when the zoom level is greater than or equal to the From value and less than the To value. When setting up adjacent scale ranges, use the same To value as the next range's From value. For example, if one range is 0 - 20,000 set the next range to 20,000 - 40,000.