This setting is available for both Threshold Types.

For line thresholds, it determines the opacity of the line, whereas for area thresholds, it will affect the opacity of the start and end borders of the area. You can choose a value between 0 and 100:

• 0%: The line(s) will be completely transparent and not visible.
• 50%: The line(s) will be semi-transparent, blending with the chart elements and the background.
• 100% (default): The line(s) will be completely opaque, fully displaying your chosen Threshold Line Color.