The Army Combat Uniform (ACU) is the current combat uniform worn by the United States Army. It is the successor to the Battle Dress Uniform (BDU) and Desert Camouflage Uniform (DCU) worn during the 1980s and 1990s. It features a number of design changes, as well as a different camouflage pattern from its predecessor. The ACU and its component materials are manufactured by the existing industrial infrastructure which produced the now-obsolete BDU.
The color scheme of the Army Combat Uniform is composed of a slate gray, desert sand and foliage green digital pattern. The color black was omitted from the uniform because it is not commonly found in nature. Pure black, when viewed through night vision goggles, appears excessively dark and creates an undesirable high-contrast image. In combat, the gray would tend to match the environment after use; for example, dust could cover up the gray. Gray is also a neutral color and thus does not tend to catch the eye as more saturated colors would. Body armor has been made to match the camouflage. The ACU's blend in extremely well in tan grassy fields and are almost impossible to spot more than 50 feet away even if the person wearing the ACU's is in the direct line of sight of the spotter.
Soldiers have reported that the nylon cotton fabric does breathe better than the cotton Desert Camouflage Uniform (DCUs) and results in a cooler uniform in high temperature climates.
The uniform features hook and pile fasteners on the pockets. Although some concern has been expressed that the noise associated with opening Velcro fasteners would give away a soldier's position in the field, this has been determined to be a minor issue that can be negated with correct noise discipline.
The cost to each soldier is $76 per uniform, compared to $58 for a BDU, but clothing allowances in soldiers' pay have been adjusted to compensate for the more expensive uniform. All insignia is at an extra cost, as are name tapes and branch tapes.
ACU material has the feature of being less visible in infrared, due to the lack of black color.
Near Infrared (NIR) Signature Management Technology is incorporated to minimize the infrared silhouette. Permanent IR IFF squares are sewn to each shoulder to help identify friendly personnel when night vision devices are used, and are protected by Velcro tabs in garrison or when not in use.
Three US flag insignia are authorized for wear with the ACU: full-color, full-color IR, and subdued IR. The US flag insignia (full-color or subdued) is worn on the right shoulder pocket flap of the ACU coat. The subdued version is only worn as directed under tactical or or field conditions only. On the ACU, the US flag is depicted with the union (stars) to the viewer's right, instead of the usual left (flag's own right); this is to give the impression of the flag moving forward with the wearer. Subdued shoulder sleeve insignia are always worn.
The jacket's Mandarin collar is worn up in combat to fit with the Improved Outer Tactical Vest (IOTV) body armor, and worn in the down position otherwise. The front closure is zippered and reinforced with velcro, designed for use with OTV. The tilted chest pockets, cuffs, and elbow pad insert pockets also utilize hook-and-loop closure. There is a three slot pen pocket on the left arm of the jacket, and blouse bellows for increased mobility.
Only pin-on skills badges are authorized for wear on the ACU, and no more than 3 may be worn at any one time. Skills tabs, such as the President's Hundred Tab, Ranger, Sapper, and Special Forces, are worn on the left sleeve pocket flap, and are also subject to a 3-tab-only rule. A tab that is an integral part of a unit patch, such as the "mountain" or "airborne" tab, is not counted against the rule. The U.S. Army Chaplaincy insignia is the only authorized branch insignia to be worn on the ACU. It is centered 1/8 inch above the right name tape. The insignia must be pinned on, not sewn on.
The jacket must not extend below the top of the cargo pocket and must not be higher than the bottom of the side pocket. Sleeves will be worn down at all times, in contrast with the earlier Army BDU policy which authorized sleeve-folding for the summer uniform.
In the field, the jacket may be replaced by the flame resistant Army Combat Shirt when worn directly under the IOTV.
Starching the uniform has been shown to cause discoloration. It enhances the IR signature, making the uniform brighter when viewed with night vision goggles.
In the past, personnel have been instructed that the uniform must be washed with a mild detergent that does not contain "optical brighteners." Detergents with optical brighteners may cause discoloration of the uniform, which would nullify the purpose of the very specific camouflage design and result in possible unwanted detection of personnel using the uniforms in combat. Some detergents have phosphorescent properties which enhance an enemy's ability to see the soldier when viewed with Night Vision Devices. However, these instructions have been retracted.
Soldiers have expressed concern about the velcro on the ACU. Dirt and mud can clog the hooks and loops or they can wear out with use, requiring the use of cleaning brushes for clearing the velcro as part of daily maintenance. Zippers have also been a topic of concern. Soldiers also express concern because the zippers (as with any zipper) can bind up, and render the uniform uncomfortable to wear, especially with Body Armor. According to the Program Executive Office Soldier "Commercial Velcro will be sold in clothing sales for the repair/replacement of Velcro. Additionally soldiers have been using the small weapons cleaning brush to clean out any sand and dirt from the pile and it has been working very well."
Weight of the ACU, like the BDU, has also come in for criticism. The ACU has numerous uniform reinforcement panels and the large number of oversized pockets, utilized primarily for reasons of durability and convenience, tend to increase heat and perspiration retention in hot-weather environments, increasing the risk of skin disease and skin inflammations in humid environments. Triple thicknesses of cloth at the thigh, the result of overlapping pocket panels, combined with overhang of the combat jacket result in additional retention of body heat. The extra cloth material tends to negate some of the evaporative benefits of the open-weave cloth construction; the problem is compounded when pockets are filled with miscellaneous items. In comparison with the already-heavy BDU, the ACU is even heavier, having been designed with heavier thread, more fabric in the seams, and stronger stitches, combined with hook-and-loop tape sections and barrel-lock closures to secure some pockets. In humid regions, the carrying of large amount of gear in trouser and shirt pockets is generally unknown among other uniformed military forces, as the practice retains excessive body heat and promotes corrosion of carried items through perspiration. Instead, gear is carried on suspended slings, attached to a accessory load belt, or carried in backpacks.
The open-weave construction of the ACU, BDU, and similar uniforms is easily penetrated by insect stingers and probosces, causing an increased risk of transmitted diseases such as malaria, even when pretreated with permethrin or other repellent. Since World War II, the U.S. military has been aware of issues with loosely-woven fabrics and open-smock combat jackets in tropical and jungle environments, and issued a tightly woven Byrd Cloth tropical uniform of single-layer Egyptian cotton for jungle troops in 1943.