Here is the helmet cable DIN plug wiring diagram for those of you who want to experiment with your own "accessories".

Looking at the connector with the index groove in the connector at the twelve o'clock position, the bottom pin is #2.
So clockwise from the index groove the pins are #6, #1, #4, #2, #5, #3, #7.

6 is the shield/ground (one o'clock postion)
1 is the microphone input (three o'clock position)
4 is the microphone ground (five o'clock position)
2 is the speaker ground (six o'clock position)
5 is the left speaker positive (seven o'clock position)
3 is the right speaker positive (nine o'clock position)
7 is the handheld PTT (eleven o'clock position)

Click here for wiring schematic photo.