The Magpul Industries MAG057-BLK Internal Core Unit enhances your MIAD, MOE, and MOE-K2 grips with maximum functionality. Engineered for seamless integration, this unit provides a storage solution for essential components. Crafted for reliability, it securely holds one complete standard AR15/M4 bolt and firing pin, ensuring you have critical parts at your fingertips when you need them. Holds one standard AR15/M4 complete bolt and firing pin Internal core unit for the MIAD, MOE and MOE-K2 grips Optimize your firearm experience with the precision-designed Magpul Internal Core Unit.