When price is 'closing above or below the 20ema then what you look for is two 'closes' in a row on the other side of the 4ema which suggests a change in the ultra short term trend. So if price is closing above the 4ema consistently with the odd one day close below then when you see two closes in a row below the 4ema you tend to see an ultra short term reversal in trend. And the opposite occurs when price is consistently closing below the 4ema and then has two closes in a row above the 4ema you tend to see a reversal in price. So the two closes on the other side of the 4ema is the trigger to exit the trend you are trading. And at the same time you should watch price to see what side of the 20ema it is on for the major directional trend. The 20ema rising or falling is the main thing and the direction to trade on but one can just use the 4ema for very short term moves. Intraday trading on 2 min charts etc gets very tricky to trade as using the 4ema in such a short term time frame you may only be scalping 1/4 to 1/2 a point using this. So just buying price as it tags a 'rising' 20ema or shorting price as it bumps up against a 'falling' 20ema works best. Depends on how fast you can make these trades and if you like scalping for partial pts I guess.