Albert

What is this part? It came with the car when I bought it new.
I know that is has something to do with the alarm system.
Does anyone know where I can purchase this part cheap or
only the Nissan dealer has this part? It has this number
on the case: PRO 9094C
This part still works. I removed it since the green wire
seems like it has broken off. There are three wires that
comes out of it...red, black, and green. Do I need to
connect the green wire? I can't remember if the green wire
was ever connected?

http://images.cardomain.com/installs...960_1_full.jpg