The YMAF-X4BD Zeigel is a prototype large mobile armor developed by the Earth Alliance Forces to realize the concepts of a conventional mobile armor: "sufficient firepower for solo missions," "mobility that rivals fighters," and "heavy armor to withstand attack." To achieve this, the Zeigel is equipped with a powerful M526 Multi-phase Energy Cannon "Marshak" as its main weapon, can fly within the atmosphere, and adopted the Positron Reflector for defense. To power its equipment, the Zeigel is installed with multiple batteries. Unfortunately, the prototype mobile armor experienced unstable power output, and either the "Marshak", the flight system, or the Positron Reflector would be inoperable whenever its power output dropped. Additionally, while it can deploy the Positron Reflector in any direction for defense thanks to having five Positron Reflector generators, the unstable power output meant that the Positron Reflector can only be generated from one generator at a time.

The YMAF-X4BD Zeigel was developed to test the viability of a modern mobile armor, however, due to its various flaws, it was virtually abandoned by the Earth Alliances Forces in a hangar at Victoria Base. During the incursion on Victoria Base led by the Zala Faction Remnants, the Alliance forces deemed the Zeigel suitable for short-term use and deployed it for defensive purposes. Attacking indiscriminately, the Zeigel targeted both ZAFT forces and Athrun Zala, forcing Athrun to destroy the mobile armor to prevent it from interfering with his attempt to save the base from an imminent nuclear strike. The design concepts and data of the Zeigel seemed to be used in the development of the YMAF-X6BD Zamza-Zah.