This a Reduced Power Firing Spring is for Glocks GEN's 1-4. This spring is manufactured by Ghost Inc. 4.0 lb. Reduced Power Striker/Firing pin springs this spring will give you the lightest possible trigger pull weights possible. Use these only for Target or competition shooting-NOT FOR SELF DEFENSE!! If you combine this spring with the 6.0 Trigger Spring and a Ghost 3.5 lb Trigger you will get a very light trigger pull. GEN's 1-4 This spring is manufactured by Ghost Inc.