"The resultant benefits of lighter weight and decreased heat retention are best suited for operating environments characterized by high elevations, thick vegetation or tropical climates," Carey said. "The reduced bulk of the vest is also well-suited for the confined spaces [that] combat vehicle crewmen typically operate in."

The manufacturer, Eagle Industries Unlimited, is under contract to produce 9,483 SPCs, at a cost of about $410 each, with about 5,500 fielded so far, Carey said. She did not say when the rest of the order must be delivered.

SPCs were first fielded in 2007 by the Okinawa, Japan-based 31st Marine Expeditionary Unit, which submitted an "urgent universal needs statement" asking for body armor more suitable to tropical environments and mountains, Carey said.

The SPC is not meant to replace the MTV, Carey said, but is an option for commanders who must decide what type of protection is best suited for a particular mission.

In February, Commandant Gen. James Conway halted an order for thousands of MTVs, adopted in 2006 to replace the problem-plagued Outer Tactical Vest, and criticized their bulky design. Still, the Corps ordered 28,000 more in August, calling them an interim solution until something better is developed.

In an interview aired Aug. 31 on "This Week in Defense News" - a television show hosted by Marine Corps Times sister publication Defense News - SysCom commander Brig. Gen. Michael Brogan acknowledged complaints about the vest, but said commanders told Conway they need it for the time being.

"We're working very closely with Marines who have come out of theater [and] Marine Corps Combat Development Command to develop that next-generation vest," Brogan said. "Ideally, we will do it with the United States Army, so that we wear the same equipment, and then we don't have to face questions from the media and Congress about who has the best equipment."