It is used to identify trend reversals. The Mass Index is a range oscillator that uses changes in trading price and provides unique market reversal forecasts that other indicators may miss. The Mass Index attempts to identify reversals by comparing the trading range between High & low prices for each period. A bulge in the index line signals reversals.
This occurs when the 25 periods Mass Index rises above 27 and falls back below 26.5. By calculating a 9 days exponential moving average, go long if there is a reversal bulge & EMA points downwards, whereas go short if there is reversal bulge and EMA points upward