1. Buy when price breaks out of the upper band.
2. Exit has two options. Option 1 allows you to exit using lower band. Option 2 allows you to exit using basis line.
3. Slippage and commissions are not considered in the return calculation.
In true TradingView spirit, the author of this script has published it open-source, so traders can understand and verify it. Cheers to the author! You may use it for free, but reuse of this code in a publication is governed by House Rules. You can favorite it to use it on a chart.