Marines with 7th Engineer Support Battalion test Improved Ribbon Bridge components with representatives from Marine Corps Systems Command, and Marine Corps Engineer School, at the test pond aboard Marine Corps Logistics Base Barstow’s Yermo Annex, Calif., Jan. 25. Function checks are performed on the IRB before it is sent to the Operating Forces in order to ensure that they receive properly working equipment, said Gunnery Sgt. Quinton Shearer, Bridging Project Officer with Marine Corps Systems Command. - Marines with 7th Engineer Support Battalion test Improved Ribbon Bridge components with representatives from Marine Corps Systems Command, and Marine Corps Engineer School, at the test pond aboard Marine Corps Logistics Base Barstow’s Yermo Annex, Calif., Jan. 25. Function checks are performed on the IRB before it is sent to the Operating Forces in order to ensure that they receive properly working equipment, said Gunnery Sgt. Quinton Shearer, Bridging Project Officer with Marine Corps Systems Command.