AIM's complete Bolt Carrier Groups for 9mm caliber AR type Firearms. Compatible with Glock, Colt, Ruger, S&W and STI style magazines. Upgraded with threaded extractor pins. Military Grade hardware that is priced for the everyman! Backed by AimSurplus's legendary customer service. The Nickel Boron coating is harder than chrome and improves the maintenance, cleaning, heat dissipation and corrosion resistance. More information below.