The Oversold and Overbought indicator paints the bars on the chart, by default the bars will either be displayed as blue or as red. The Oversold and Overbought indicator uses the Average True Range (with a multiplier of 2) in its calculation to determine the colour of the bars.
This is a companion discussion topic for the original entry at https://www.optuma.com/kb/optuma/tools/berg/oversold-and-overbought