EEMANN TECH UPGRADE KIT FOR GLOCK GEN3, 4, 5. The Eemann Tech Upgrade Kit for GLOCK GEN3, 4, 5 Small Frame allows you to lighten the trigger pull weight of your GLOCK and extend the magazine catch that allows to reduce the time of magazines reloading. The GLOCK trigger pull weight is determined springs weight and GLOCK OEM connector 4,5 lbs. (2.0 kg). The Eemann Tech Upgrade Kit for GLOCK GEN3, 4, 5 contains: • ET-121003 - Eemann Tech GLOCK Firing Pin Spring (Reduced power) - This spring lightens the work of the trigger mechanism. • ET-121004 - Eemann Tech GLOCK Trigger Spring (Heavy) - This spring helps you to pull the trigger easier. • ET-121005 - Eemann Tech GLOCK Firing Pin Safety Spring (Reduced power) - This spring lightens the work of the trigger mechanism. • 721 - GLOCK OEM Trigger Pull Connector 4,5 lbs. (2.0 kg). • 8794 - GLOCK OEM Magazine Catch Extended for GLOCK GEN4 Small Frame. Please note results may vary due to different tolerances in individual pistols