Technology & Combat Characteristics
A variant of the Astray Blue 2nd Revise, it is equipped with the Full Armor Phase Shift (FAP) system that is given to Gai by a third party for a mission near the sun. Besides the FAP system, the Blue Frame Fourth also has a different head unit, and shoulder armor that are the same as those used by the original Gundam Astray Blue Frame. The FAP System consisted of Phase Shift armor plates, independent battery unit, ablative gel heat protection system, additional thrusters units and a pair of laser cannons; it can also switch between two modes – High Speed Mode for improved speed and thrust, and Full Armored Mode for better protection from the sun's intense heat. In terms of weapons, other than the laser cannons, the suit also has a large vulcan on its head, six "Armor Schneider" combat knives on its body, and a pair of arm-mounted short rifles.
History
Some time after the end of the war between Naturals and Coordinators, Serpent Tail was employed by an unknown party to destroy a cannon that is near the sun. It is unknown who or what organization created this cannon, but it is aimed at Earth. To accomplish this difficult mission, the employer gave Gai the Full Armor Phase Shift (FAP) system.