The System-∀99 ∀ Gundam (pronounced as "Turn A Gundam", aka "∀", "White Doll" or "Mustache") is the titular mobile suit of Turn A Gundam. It is piloted primarily by Loran Cehack.

The Turn A Gundam was originally created for interstellar warfare in anticipation of invasion of forces outside the solar system and said to be the culmination of super-advanced technologies from generations past. As opposed to other weapons which were created to meet a specific purpose, the Turn A's design was unusual and built entirely on the premise of "single-machine operation", with the versatility to perform all military operations on its own. Owing to the fear of extrasolar forces, the Turn A was constructed with all restrictions of the development of weapons removed, and as a result no longer fits into the concept of a weapon.

Unlike other mobile suits (even those that predate the Turn A itself), the Turn A is powered by a DHGCP (Discontinuous Hyperoscillation Gauge Collapsing Pile) power plant in its abdomen, which is essentially an artificial black hole. This is used in conjunction with an innovative reactionless I-Field Beam Drive system to move the suit's limbs and provide thrust. As a result, the unit's chest is almost entirely hollow and can equip various weapons inside, such as missiles or beam cannons. The legs are also hollow due to the use of the I-Field Beam Drive, and contain an array of thruster vanes which are used to power the suit's jumps and flight. This leaves the back of the unit free to store more weapons and equipment if desired. The Gundam's armor is also covered with self-repairing nanomachines, dubbed "Nanoskin".

The Turn A's armaments consisted of a beam rifle, two beam cannons, two beam sabers and a shield. It can also mount various weapons (such as missiles) in the chest to compliment its basic weaponry. It can also use a powerful I-Field capable of covering a large area and affecting matter. To further enhance its combat power, the Turn A has support areas called DOC Bases (Device Operation Control) which hold various armaments, enabling it to adapt to the situation at hand by equipping a variety of weapons. One of these DOC Bases was discovered in C.C. 2345. However, the base had been sealed and not maintained by any nanomachines during the thousands of years the Turn A was buried, so almost all its weapons crumbled upon exposure to air. The only weapon still usable was a hyper hammer that was simple and thick enough to remain intact for a short while without maintenance.

The Turn A's on-board nanomachines are capable of a devastating attack known as the "Moonlight Butterfly" (named after the visual appearance of the attack). The Turn A's nanomachines have the ability to disintegrate all matter that includes artificial objects as well as organic materials, and can merge with weather systems to create large ionic storms capable of covering a much wider area. These nanomachines can be used offensively or defensively for all range attack and defense. The nanomachines are capable not only of destroying technology however, but of maintaining and repairing it too. This ability is not instantaneous though, and it requires a considerable amount of time. The back weapon pallet of the Turn A was originally planned to be equipped with weapons based on the Seventh Generation Minovsky Physical Theory (7th-GMPT), a nondestructive MS-incapacitating technology, during the conceptual phase of the "System ∀". However, the development of such weapons was not completed in time for the demonstration test for "System ∀", and so beam sabers were provisionally installed for melee combat.