SureFire Optimized Bolt Carrier Group for Direct-Impingement M4/M16/AR-Variant Carbines
Invented by Jim Sullivan, one of the original designers of the M16, the SureFire Optimized Bolt Carrier (OBC) is designed to improve the functionality of an M4/M16/AR variant weapon system during both unsuppressed and suppressed firing.
www.surefire.com
I'm sure they'll sell out. Lol