The design that started a movement. When we developed the first version of our signature shirt, we had no idea that it would lead to such widespread adoption of our basic design. The G3 COMBAT SHIRT™ is a combat-specific garment specifically designed to be worn under body armor. It keeps you cool with wicking, lightweight, high-performance, flame-resistant DRIFIRE® torso fabric and reinforced Mil-Spec 50/50 NYCO ripstop sleeves.