Aimed at forces personnel the challenger bags are designed to offer excellent insulation whilst at the same time reducing bulk and weight. The bags are filled with the new High Tech 3D Micro a polyester micro fibre which offers superb insulation in all conditions, allowing the bags in this range to maintain a high degree of performance even when wet. The outer and inner are made from super soft but durable polyester 210T micro ripstop fabric , with an Oxford Polyester reinforced foot section.