It's a advanced version of the regular Parabolic Sar EA. The difference is that the double PSAR EA version is able to use 2 timeframes to filter the trades. For example - you attached this EA on M15 chart, but you also want to have a confirmation from 1H timeframe as well, this EA is able to do that. Both charts must be bullish or bearish. Basically you can scalp on smaller timeframes, but also have a confirmation from the bigger timeframes. Still you can use this version as the regular version - set timeframes as default. Also you have ability to use any timeframe to close the trades once the trend has changed. This PSAR forex robot is quite simple, but at the same time it may be very profitable and interesting to play with.