This indicator shows how much will the price need to go to fill its Average Daily Range based on the last 5 days (before today).
5-day ADR is used in concepts by ICT, Poltoratskiy and number of others.
Generally speaking, we would like to enter when there is a lot of room for price movement.
Outer lines are a full expansion. If the price moves only upside from the opening bell, it will reach as far.
Inner lines are a remaining expansion required to hit ADR. If the price initially moves in one direction and then reverses, this drip is substracted. This is more important metric!