This is one of the Gundam Cannon variations of the mass-produced Gundam.

The Gundam Cannon attempted to increase its firepower by equipping the BCP (Back Cannon Pack), but this risked sacrificing mobility.

This particular unit has only one cannon, with the other equipped with a single beam saber, in order to preserve some mobility.

The '1' in the model number indicates one cannon; the original version, equipped with two cannons, is distinguished as the 'CN-78-2 Twin Cannon Specification'.

By making the equipment selectable in this way, it allows for combat suited to the pilot's strengths.

CN-78-1 Gundam Cannon (Single-barrel specification) | ルイ's Gunpla works