Square aerial on the top of a T6.1, DAB? GSM? GPS? What is it?

[B3NNB]

I need to move my aerial from the front of the van to the rear. I've found a 3m fakra extension, but what is it for? If it's for SOS I won't bother relocate as it's disabled and just seal the hole.
But if it's for something else I'll move it.
Thanks in advance.

 

[Aron]

I think its SOS. Aerial still in the mirror.