The slow relative strength index (SRSI) indicator created by Vitali Apirine is a momentum price oscillator similar to RSI in its application and interpretation. Oscillating between 0 and 100, it generates both OB/OS signals and midline (50) cross over signals and divergences.
As author suggests, bullish/bearish divergences generated by SRSI are not as effective during strong trends. To avoid fading an established trend, the system is used in conjunction with a trend confirmation tool like ADX indicator.
You can configure the OB/OS levels, default are 70/30.
More info: The slow relative strength index, TASC 2015-07