Soldiers wear the flame-resistant (FR) Army Combat Shirt (ACS) under their body armor instead of the Army Combat Uniform or the Army Aircrew Combat Uniform jacket and standard-issue T-shirt. This reduces bulk for Soldiers operating in extreme climates.
The shirt torso features a highly breathable, moisture-wicking cotton/rayon/polyester/spandex blend. It increases moisture vapor transmission, heat stress relief and comfort when worn with the Improved Outer Tactical Vest. The FR sleeves are in the Universal Camouflage Pattern or Operation Enduring Freedom (OEF) Camouflage Pattern (OCP). They have integrated anti-abrasion elbow pads, shoulder pockets, infrared identification tags, and hook-and-loop fasteners for the name, rank, unit patch and American flag. The shirt also features flat-seam shoulders and side panels for comfort, a state-of-the-art FR process fuses to the fibers. It is washable and maintains its flame resistance for the life of the garment.