The Geissele Reliability Enhancement Kit includes the Geissele Reliability Enhanced Bolt Carrier Group and the Geissele Super 42 Braided Wire Buffer Spring & Buffer in your choice of H1, H2 or H3 configuration for 5.56mm AR-15 pattern rifles. The Geissele REK is the culmination of a many years of extensive testing and fine tuning to bring you the most reliable operating system upgrade you can make to your carbine. Specifications for Geissele H3 Reliability Enhancement Kit: Manufacturer: Geissele Color: Black Fabric/Material: Carpenter 158 Caliber: 5.56mm Gun Model: AR-15 Hand: Right Carrier Material: Carpenter 158 Package Contents: Geissele H3 Reliability Enhancement Kit