These Bollinger Bands are exponential because the variance is calculated using the exponential moving average, rather than just adding the normal standard deviation to the ema. This may be more useful because the exponential standard deviation should be more sensitive to near term increases or decreases in volatility.
Please do not forget that Bollinger Bands...
Simple indicator showing market hours for New York, London, Sydney and Tokyo. It plots 60 bars in future so you can easily see when certain sessions start or end before it happens.
x = gap between plots (adjustable)