AT4-CS(Anti Tank 4-Confined Space) is the upgraded version of the AT4 purchasable with cash point.
The AT4-CS has solved the bug of back blast from original AT4, allowing it to be fired in confined spaces. This weapon deals higher damage than the original weapon and is available for use in all modes. Moreover, its rocket is homing to the target. It could deal up to 1000 damage per round to zombies.
After the 4 December 2014 update of South Korea, Item Battle was rebooted, and this weapon became a special item which can be picked up in this mode, alongside Ripper. It is protected in a yellow barricade which must be destroyed to obtain.
The special AT4-CS features a transparent skin, which is different with the normal ones, for easy recognizing. It also has 30 rockets in total and can be fired without reloading.