Bollinger Bands shown with a horizontal basis, to make it easier to see how volatility is changing and identify squeeze opportunities.
There is a histogram (purple) which shows how the basis is changing, and a price line (yellow) showing the location of the price within the bollinger bands.
It is tuned to 2 STDEV, but shows the area within 1 STDEV a different color to help visualize when the price is near the extremes of the bands.
By default this uses an exponential moving average to calculate the bollinger basis, but this can be changed in the options.