This is the starting color for the LED. It's best to use the advanced picker and use colors that are direct. For instance Red being RGB 255, 0, 0. This color will blend into the end color via interpolation.
This is the last value where change is seen. For instance set to RPM starting at 1000 intensity 0 and ending at 2000 intensity 100 will get brighter as the RPM increases between 1000 and 2000. It will stay at intensity 100 after 2000 until the warning or cutoff values take over.
This is the value in which the LED is to be turned off completely. This can be used to have an LED only on for a certain range or only warning at a certain range if you're creating a blended sweep across the LEDs.