Basically, the pins that the trigger pivots around are changed out for wider ones, changing the tolerances for how far the trigger needs to be pulled to release the bolt/firing process.

So I installed it and tuned it today, I am happy with it, but its not quite what I expected. It definitely does make the trigger faster, but not light enough to walk it. It definitely improves BPS and I'll see if I can get a video in to show you guys. I would say its just barely worth the $20.

It's nearly impossible to walk a trigger that's not electronic.
I have seen people who can shoot really fast with mech double triggers, but never "walking" like you have to do in semi-only speedball.

Oh I believe that for sure. I can shoot really fast even with just the double trig... I out shot my friend's BPS and he has some fancy electric gun.