Introduced in the early 2000's, the ACU (Army Combat Uniform) is current United States Army forces battle uniform, consisting of combat shirt and cargo trousers, and the successor to both the classic Battle Dress Uniform (BDU) and Desert Camouflage Uniform (DCU). Comparing to its predecessors, it features a number of significant design changes along with a different camouflage, with UCP camo being its official pattern, although the MultiCam version was also issued lately. Among many improvements applied in the ACU shirt is the Mandarin collar (worn up or down) and zippered front closure reinforced with Velcro, as well as tilted chest pockets, cuffs and elbow pad insert pockets, also with hook-and-loop closure. What is more, there is a 3-slot pen pocket on the left arm of the jacket and Velcro attachments to secure items such as name tapes, rank insignia and shoulder patches and tabs. Available at the UK based Military 1st online store is a wide selection of ACU shirts and cargo trousers, from such manufacturers as Helikon, in a range of colours and camouflages, including woodland camo, MultiCam and popular A-TACS AU pattern.