The kit includes GUND bits, which can be displayed in combination with two sets of the Mercury Witch Weapon Display Base, sold separately. Additionally, the kit comes with the Variable Rod Rifle, a long portable firearm that serves as the main weapon. A clear colored escutcheon and a display base are also included.

Developed by the Vanadis Institute, it was one of many prototype units created alongside the Lfrith before the establishment of GUND FORMAT technology. The Calibarn took a radically different approach compared to the Lfrith, prioritizing mobile suit performance to push the limits of GUND-ARM capabilities. This approach came with extreme measures that did not ensure the pilot’s safety, highlighting its risky and ambitious design philosophy.

Despite its innovative design, the Calibarn lost to the Lfrith in the development competition. As a result, all records of the Calibarn were destroyed, and it was sealed away, becoming a symbol of ambition and caution in the realm of GUND-ARMS. Public sentiment towards the Calibarn has been mixed, with some considering it the most cursed of all Gundams due to its controversial history and the dangers it posed to its pilots.