The PRO 3.3 is Smoother, Lighter, Shorter and eliminates trigger Over-travel! These attributes give you the fastest most accurate first shot hit advantage of any self-defense Glock style trigger. 2 Ounces lighter than the EVO ELITE The Pro requires the Trigger Control Tab (TCT) to be trimmed a little bit at a time until the weapon dry fires. Once it is fit the limited movement beyond the firing pin release will correct your right or left drift.