This is a Apex Tactical Specialties Kit, model 100-056.
The Apex Action Enhancement Trigger & Duty/Carry Kit for the M&P Shield (9/40 only) is a combination of the Apex Duty/Carry Kit and the Apex Action Enhancement Trigger. This kit delivers a significantly improved trigger pull in the Shield without compromising safety.
Features:
Reduces trigger pull by approximately 2 lbs.
Smooth uptake and reset
Reduces pre-travel, over-travel and reset
Maintains factory safety values