The JP 9mm Bolt Assembly fits Colt 9mm style AR-15 and M16 rifles. This bolt has been tuned by JP to ensure consistent feed, extraction and ejection. Can be used in conjunction with the JP 9mm Silent Capture Spring, for the ultimate in tunability and smooth operation. The bolt features a matte black finish, and includes all internal combonents, composing of the firing pin, firing pin retaining pin, extractor and firing pin spring. Mfg: J P Enterprises SPECS: Fits - 9mm AR Plateform designed to accept GlockA(R) magazines.