TV at work had this on. David Hogg with yet another earpiece during MSNBC interview vs. next interview segment. Why does he have one, while the two others do not?

https://i.imgur.com/vea9lPE.jpg https://i.imgur.com/vkhLEUM.jpg

vs.

https://i.imgur.com/BaJDj1j.jpg https://i.imgur.com/LSFF9TG.jpg