The CATTB (Component Advanced Technology Test Bed) was an experimental American main battle tank developed in the late 1980s. Built on a modified M1 Abrams chassis, it served as a testbed for future armored technologies. Its defining feature was a massive 140mmXM291 smoothbore gun equipped with an autoloader, paired with an advanced hydropneumatic suspension and an upgraded engine system.

In-game you can obtain it from crates. It’s literally upgraded version of default M1 abrams hull, but it differs from the SEP v3 in that its engine is quieter and there is no ARAT ERA on sides making your sides very vulnerable.