Go for long if Easy R Cross the 20 level from below to above. Tight Stoploss will be the low of the LAST RED candle's low point.
Go for short if Easy R Cross the 80 level from above to below. Tight Stoploss will be the high of the LAST Green candle's low point.
Do not modify or play things with stoploss. Low risk High reward trading system.
Best time frame - depending on only you. For intraday I personally use 5 min time frame.