The poncho liner consists of nylon outershell encasing a polyester loft filling. With ties. Official Government Issued poncho liner. Fits under many ponchos. Originating in the United States military intended to provide warmth in mild temperatures used as an expedient sleeping bag when attached to the standard issue poncho. Troops generally hold the poncho liner in high regard, as a very useful piece of equipment, light and packable yet reasonably warm. Woodland Camouflage - GI poncho liner .