Heated, Electric seat black plug wiring

[matk7920]

Hello, I'm swapping seats from a4 b8 to a3 8p. I'm struggling to understand wiring of back plug of seat. I figured out wires for:
-seat occupancy sensor
-seat belt sensor
-ground
But I don't understand why there is a red wire, I found out it connects to that little thingy at the end of seat rail, but I don't know what is it. I searched through all my sources of knowledge and found no answer what that tiny friend is...
I was able to read part number from it:
1k0960341
I prepared wiring for seats, but I don't know is that tiny thing necessary? In my a3, I don't have something like this. Could somebody tell me what is it? Do I need it in a3?(Photos of plug and tiny thing below) Thanks in advance! Take care!

Wysłane z mojego SM-G973F przy użyciu Tapatalka

[Smac770]

If it's going to the sensor on the longitudinal seat rail, it's the seat position sensor for the airbag controller. So it knows how close or far from the airbag the seat is currently positioned.

The 8V doesn't use dual igniter adaptive airbags, so there's nothing to modulate anyway. So makes sense an 8V doesn't have such a sensor.