Can anyone explain Zlatan Ibrahimovic’s choice of undergarments?

Paris Saint-Germain played a friendly on Saturday, after which Zlatan Ibrahimovic took off his kit to reveal what you see above. If you have an explanation, we’d love to hear it. Below, bonus video!

Edit: It’s a player tracking device! Lots of other players wear these, so it’s still not an explanation, because I’ve never seen this model before.