The Apex Duty/Carry kit for the M&P shield was designed to provide the shield pistol owner a smooth, consistent trigger pull that is approximately 2 lb lighter (based on variations in factory tolerances) with the advantages of shorter over-travel and more detectable trigger reset. All of the components work together to provide a pull weight within the acceptable range for a top end, service pistol. However, armorer or gunsmith installation of the ultimate striker block (USB) into the shield slide is strongly recommended. Features: Reduces trigger pull by approximately 2 lb Smooth uptake and reset Reduces reset length Reduces over-travel