This is the Geissele Super Semi-Automatic (SSA) Trigger. The SSA fits standard AR15's and is a non-adjustable combat trigger meant to perform like a match-grade two-stage trigger, allowing for the most precise and accurate trigger control. A trigger like this is recommended for demanding applications, such as Squad Designated Marksmen (SDM) rifles, Law Enforcement use, or Close Quarters Battle (CQB), and mid-range carbine work.
So what are the advantages to you as a shooter?
The initial force needed to start the disengagement of the sear surfaces is low and the force linearly increases at a low rate. This helps the shot to fall at the initial point of aim, and will aid in building shooter confidence, as well as the ability to put the rounds where the shooter's sight is pointing. The SSA's pull weight and sear engagement are non-adjustable by the shooter, only 2.5lbs on the first stage and 2 lbs on the second stage, giving you a total pull-weight of 4.5lbs. The trigger will allow the shooter to slap through the the trigger-pull on close-in shots, but also set up long-range shots with a crisp trigger break.
Safety-wise, the Geissele SSA Trigger has advantages, since it's a 2-stage trigger, it contributes to safety and low tendency of any inadvertent movement of the trigger to discharge the weapon. The patented pseudo-sear prevents the hammer from falling unless the trigger is pulled, and trigger-timing isn't altered due to dusty, abrasive environments, as it's meant to operate in those situations.
Changing out your stock trigger for the Geissele Super-Semi Automatic may seem like a big deal, but thanks to Bill Geissele, there are many tutorials on their YouTube page to easily guide you through the install process.
To read more details about the SSA, check it out on GideonTactical.com.