High - Low Bollinger Bands These work better than the standard Bollinger Bands for setting extreme ranges.
What I use these for is to use an oscillator to find an buy / sell signal then take that to the H L Bollinger bands and mark the spot. Most of the time, you will find that the price does not exceed this spot for the duration (length) of the H L Bollinger bands.
This makes them good for doing Credit Spreads such as Put Vertical Spreads and Call Vertical Spreads. Since the price will normally not exceed the bands at the extreme point, the trader can profit from the time decay and other factors.