What is this?

I recently picked up a used 2016 Tundra SR. The previous owner installed an antenna on the upper, center of the windshield, wires run up into the headliner. I was not given any remotes, just 2 keys. The dealership tells me that I cannot order a factory remote door lock key fob for my truck but I have power locks.
Is this antenna for remote start or door locks? The antenna says HX Plus and OK/15H on the side sticker. Anyone have ideas?

 

That is the antenna for this remote start.

 

Ok, so theoretically I could purchase a replacement remote and it 'should' work?

 

If everything is hooked up.

 

Cheap remote start. Hopefully the replacement fobs don’t cost what the unit does.

 

Had the same thing happen to me once when I bought a used honda , never got any fobs and noticed the antenna on the windshield , checked the module # and did some research , tracked down a remote on ebay and programmed it and everything worked ! best of luck with yours

 

Just spoke to a car audio etc guy and he gave me some things to look for. I have to see if they left the brain and other parts.