I've noticed the Evolution of the Impulses from the oldest models to the newest models.. My model of impulse is 3189, I notice that on the side of my gun, there is actually a slot where u can see the electronics.. I look at my friends pulse (a 4150) and I notice that the slot is gone, along with some other holes that are now closed up... I was wondering if that slot that I can see the electronics was suppose to be somethin where u could plug somthin in or somthin?.. Im not sure, I just know that it sucks to have paint in there cuz it gets all over the board.. Anybody know why they closed it up?, or why they even had it there in the first place?