The NR 7 is a very potent candlestick - what NR 7 means is narrowest bar in last 7. And that means that the trading community will probably change directions on the next bar.
Here is SAI from Friday -
Many of the packages on the market that will observe intraday candles will pick out the NR 7 candle for you and send you an alert. For that reason those particular packages are probably worth their weight in gold.
I don't particularly play that trade unless it pops up on one or more of the stocks that I follow regularly - then I will take it. The reason for that is that I feel more comfortable with my farm than I do with new candidates that I haven't observed in action.
The way to play an NR 7 is simple - if the stock has been declining (and it can be used in the Return to 4 method) buy the stock on the breakout of the next bar and put your stop below the NR 7. If you see it form an NR 7 and you own the stock it is probably time to sell.