Wristband Helps Team Win

I have been following the young athletic teams at our local school for many years.  All my kids participated in those teams, as have my grandchildren.  I decided to go to a game a few weeks ago and was amazed at how the team had so many youth flag football plays.  The lady next to me was talking about how this new wristband has been helping the team win so many games.  I asked her what she meant by that and she told me it is an electronic device that the coach uses to figure out the strategies against the other team.  She says it is really neat and that if I wanted to know more to go online and look it up.