This indicator displays the pre-market volume (note: without the post-market of the previous day).
Unusual pre-market volume often indicates that institutional market makers are moving the market, which is a good sign for unusual high price movement.
The indicator helps me to spot stocks, if a pre-market gap is confirmed with enough (unusual) volume.
You can define, what "unusual" means by you, by adjusting the SMA length and the SMA multiplier.
The default is a length of 21 bars and a 2.5 multiplier, meaning I'm interested in a stock, if the pre-market volume exceeds the average pre-market volume by 2.5 times.