The AT4 (also variously AT-4, AT4 CS, AT4-CS, or AT-4CS) is an 84-mm unguided, portable, single-shot recoilless smoothbore weapon built in Sweden by Saab Bofors Dynamics (previously Bofors Anti-Armour Systems). Saab has had considerable sales success with the AT4, making it one of the most common light anti-tank weapons in the world.
The designation "CS" represents "confined space" referring to the propellant charge being designed to operate effectively within buildings in an urban environment. It is intended to give infantry units a means to destroy or disable armored vehicles and fortifications, although it is not generally sufficient to defeat a modern main battle tank (MBT). The launcher and projectile are manufactured prepacked and issued as a single unit of ammunition with the launcher discarded after a single use.