Another bling thing, when I first fired with it I thought oops this might be illegal.
I used a sound meter app and did some tests with subs, 10 with and 10 without.
Without averaged 94db, with averaged 94.5 because there was one 100db in the string.
It’s like the difference between someone talking with their back to you and someone doing the same with their hands cupped around their mouth to project the sound.
The fact that it seems to sweeten the harmonics is an unexpected boner, er bonus.
Basically adds a set screw to the front of the trigger and pre loads it. I haven’t used a lighter trigger spring but i just found the creep on mine to be terrible. It’s one of the very first 2014 rifles out so probably worse than they are now.