The Army Combat Shirt (ACS) is a flame-resistant combat shirt developed by the U.S. Army as a complementary component to the ACU (Army Combat Uniform). It is designed as a standalone garment for use under the IOTV (Improved Outer Tactical Vest) in warm and hot climates. The shirt was officially introduced in 2007.

ACS was engineered to significantly enhance soldier comfort by using lightweight, breathable, moisture-wicking materials. It was developed in cooperation with the U.S. Marine Corps as part of the FROG (Flame Resistant Organizational Gear) program. Combined with FRACU flame-resistant trousers, it offers burn protection from the neck down to the ankles.

The shirt is made from advanced FR fabrics that will not ignite when exposed to open flame. Although the material may char, it does not melt or flash. It is lightweight, breathable, moisture-wicking, and offers four-way stretch with an ergonomic fit.

Each shoulder features a zippered pocket with fabric pull tabs that remain easy to operate while wearing gloves. An additional pen pocket is located on the left forearm.

The shoulder pockets are equipped with hook-and-loop panels for patches and identification markers. The left panel includes a 2.5 cm (1 inch) vertical flap concealing a black infrared IFF (Identification Friend-or-Foe) identifier. The flap can be secured open or closed depending on the need for concealment or recognition during night operations.

The elbow area is reinforced with durable, rubberized SuperFabric®, which increases abrasion resistance during crawling, prone shooting, or extended contact with rough surfaces.

A seamless shoulder design minimizes friction under body armor. Wrist cuffs are adjustable with hook-and-loop fasteners.

Material composition:

• Torso: 43.5% cotton, 43.5% rayon, 8% spandex, 5% polyester

• Chest fabric: 47.5% cotton, 47.5% rayon, 5% spandex

• Sleeves and side panels: 95% cotton, 5% spandex

• Elbow pads: SuperFabric®

Weight: 440 g