Reduces over-travel; Smooths trigger pull; Reduces trigger weight by approximately 4lbs (based on a starting trigger pull weight of 7.0 to 8.0 lbs.); For competition use only; Works with the S&W M&P 9mm, .357SIG and .40S&W; Full Size, Compact, Long Slide and Pro models; Does NOT function in the M&P .45ACP or in the M&P Shield; NOT for use in the M&P M2.0 models; Includes: Sear, Competition Striker Spring, Competition Spring Set (Trigger Return Spring, 1/8" Sear Spring), Ultimate Striker Block Kit (Striker Block, Spring and Talon Tactical Tool), Slave pin