This version of Bollinger Bands measures the average volatility. By taking the 75th percentile of the average absolute value of the difference between the Source and the Mean divided by the Standard Deviation and using that as our multiplier for our Bollinger bands we can have a statistically safe trading zone.
You notice that its dynamic, this is because it take into account the real volatility levels of a window and uses that to determine an appropriate multiplier. As always I hope you enjoy this release.