Supposed ta help the 9 trigger pull issues some have.

My was fine after break in, but I figured WTH for $16.

https://www.mcarbo.com/kimber-micro-9-trigger-spring-kit.aspx

Install video on the site, but it's just a lighter FP spring and hammer spring.

Ain't shot it yet, but it launched a pencil to the regulation distance.

Definite improvement.