Approximately 12 items are part of the CQB upgrade program, which is designed to extend the servcice life of the M4 and simply enhance the carbine's overall performance with Commercial Off-The Shelf Solutions (COTS). Look to Fed Biz Opps and insert "CQB" as a search parameter. You'll get everything you need there. the only item dropped, unfortunately from the CQB program was the enhanced flash hider requirement. the logic behind dropping the flash hider for the CQB program (at this point in time) is to be found in another Army ARDEC program encompassing a family of sound and flash suppressors for all small arms. The Army didn't want to adopt a given flash hider for the CQB variant, only to to have compatibility problems later should a forthcoming suppressor require a different flash hider/suppressor interface.