A 91-Tango is a military occupational specialty (MOS) in the U.S. Army designated for a "Tactical Power Generation Specialist." Soldiers in this role are responsible for the operation, maintenance, and repair of various types of power generation equipment, ensuring that electrical power is available to support military operations. This includes working with generators, distribution systems, and associated electrical equipment. The MOS is essential for maintaining energy supply in the field, particularly in combat or remote environments.