The M1 Abrams is a third-generation American main battle tank designed by Chrysler Defense. Conceived for modern armored ground warfare and now one of the heaviest tanks in service at nearly 68 short tons, it introduced several innovative features, including a multifuel turbine engine, sophisticated Chobham composite armor, a computer fire control system, separate ammunition storage in a blow-out compartment, and NBC protection for crew safety.
The M1A2 was a further improvement of the M1A1 with a commander's independent thermal viewer, weapon station, position navigation equipment, and a full set of controls and displays linked by a digital data bus. These upgrades also provided the M1A2 with an improved fire control system. The M1A2 System Enhancement Package (SEP) added digital maps, Force XXI Battle Command Brigade and Below (FBCB2) Linux communications system capabilities for commanders, and an improved cooling system to compensate for heat generated by the additional computer systems. The M1A2 SEP also serves as the basis for the M104 Wolverine heavy assault bridge. The M1A2 SEPv2 (version 2) added Common Remotely Operated Weapon Station (CROWS or CROWS II) support, color displays, better interfaces, a new operating system, better front and side armor, and an upgraded transmission for better durability.