Steelers HC Mike Tomlin had a one-word response to the green dot:

It’s been less than a week since Pittsburgh Steelers quarterback Kwon Alexander became the owner of Green Dot.
Now that his season is over, who will the Steelers face this week against the Cleveland Browns?
Pittsburgh Steelers coach Mike Tomlin gave a very succinct answer: “Undecided.”

You may have seen the green dot, but if you don’t know what it is, here it is.
Defensive players with green tags (usually linebackers or safeties) have a one-way communication system with their receivers.
And there’s a speaker inside the helmet that lets you hear the coach’s instructions.
He has the important responsibility of delivering these parts to his unit.
In the early days of the NFL, there was no on-field communication between players and coaches, only hand signals.
The system has gone through several iterations since it was invented by two Cleveland Browns fans in 1956.
This ensures that devices are constantly on the same page and significantly reduces the need for latency. The referee’s alarm will stop before the start of the shot (or when only 15 seconds remain on the game clock).