The Stern Defense 9mm AR15 Complete Bolt is engineered for precision and reliability crafted from robust 8620 AISI steel and finished with a durable MagPhosphate coating. This bolt is designed to seamlessly fit MilSpec and Glock-pattern upper receivers and is compatible with both Colt SMG and Glock magazines. It arrives fully assembled including essential components like the firing pin spring and extractor ensuring optimal performance right out of the box. Enhanced with a proprietary center and roll pins this bolt is perfect for those seeking a superior fit for single-stage triggers with short resets setting it apart as a top choice for AR15 and M16 enthusiasts.