W210 things above seat belt guide?

[Parrot of Doom]

What are the plastic wedge things located on the B-pillar, just above the seatbelt guides? They appear to have two small windows.

Something to do with the alarm?

Also, my door handle has a little IR window that I believe is for raising the windows when out of the car. Trouble is, I can't get it to work. Is it an option?

 

[nickmann]

The wedgey thing is the movement detector - it is positioned to notice an arm reaching in through the windows.

the window on the door handle is indeed for comfort closing as you suggested. Try cleaning the IR window, and the one on the key. Also, note that the range is very short, only 2 or 3 metres, and you must point the key sirectly at the sensor, and the doors must be closed. There is a delay of a second or so before anything happens.