Effectively Reduces Trigger Pull
Reduced power trigger return spring pak (draw bar plunger spring) offers 3 different springs to help improve double-action trigger performance in all Smith & Wesson centerfire semi-automatics in 9mm, 10mm, .45 ACP and .40 S&W calibers. Pak contains 1 each of 2.5, 3.0 and 3.5 pound reduced power trigger return springs to allow varying adjustment of the trigger. The factory spring is 4 pounds. WARNING: Springs are for competition use only - NOT for duty use. Not for model 52-2 and Sigma Series.
Big Book Catalog, Issue:66, Page:218