The Magpul Grip Core MIAD/MOE Bolt & Firing Pin Core is the internal core unit for the Magpul MIAD, MOE and MOE-K2 Grips. The core was designed to hold one (1) standard AR15 / M4 complete bolt and firing pin. Not recommended for use with the MOE+ grip due to its slightly smaller internal dimensions required by the rubber overmolding. Made in the USA.