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Bollinger Bands (BB) usually expand quickly after a volatility increase but contract more slowly as volatility declines. This extended time it takes for BB to contract after a volatility drop can make trading some instruments using BB alone difficult or less profitable.
In the October 1998 issue of "Futures" there is an article written by Dennis...
![BTCUSD: DEnvelope [Better Bollinger Bands]](https://s3.tradingview.com/d/dK1uhbN8_mid.png "DEnvelope [Better Bollinger Bands]")
