The Apex SD Spring Kit produces a smoother trigger pull and improved reset and is designed for Duty/Carry use. It reduces the trigger pull weight by approximates 2 pounds from the factory weight and helps to improve the rest as well. The kit works as a stand-alone or in conjunction with the Apex SD Polymer Action Enhancement Trigger.Notes:Works in conjunction with the Apex SD Polymer Action Enhancement Trigger. NOT for use in the Sigma Series pistols. This kit DOES NOT include a sear spring. Apex designed this kit to work with the factory sear spring, so removal and/or replacement of the sear spring is not necessary.Kit Includes:Apex Trigger Return Spring Apex Striker Block Spring Apex SD Striker Spring FeaturesReduces trigger pull weight by approximately 2.0 lbs. from factory Smooths trigger pull Improves reset