Stop and reverse alerts, or parabolic SAR, is a technical indicator originally devised by J. Welles Wilder, Jr as a trend seeking alert.  This is a great indicator when a market is trending, but is prone to whipsaws in a non-trending market.  Wilder recommended looking for a trending market using his ADX and then finding trades using the SAR.  Some people use the SAR more effectively as a trailing stop loss to keep prices with in the parabolic curve during a trend.  Pairing the ADX or even the linear regression slope with SAR can help eliminate the whipsaws it is prone to providing.