This flat trigger is designed to fit in the frame very tightly.  It rotates on a solid pin instead of a roll pin which controls the movement.  The Pre- and Over-travel adjustments are highly improved over the factory trigger.

The trigger comes complete with trigger lever, pin, nut, trigger return spring, pre- and over-travel screws.  It also comes with a lighter trigger plunger spring.  By replacing the factory trigger plunger spring, you will reduce the pressure from the trigger plunger on the trigger bar.