Wolff Springs the Industry Leader for nearly 60 years makes these springs!  Yes, 60 YEARS! Who ya gonna trust?  Wolff Springs "the industry standard" or some company that has no track record?  Your choice.  However, Wolff Springs "the Industry Standard" seems like the easy decision.This kit contains the correctly calibrated springs you need to lower pull weight to 2.0 to 3.5 lbs when used with a 3.5 lb Connector and improve the pull quality of your Glock pistol without permanent alterations. Installing this kit will not disable or diminish the effectiveness of the well-proven Glock Safety System. Designed specifically to meet the needs of competitive shooters; this alteration is not recommended for duty pistols.