From the GoodSmile website:
An alternate version of 'Chamber'.
From the anime series "Gargantia on the Verdurous Planet" comes a special PLAMAX model kit based on the "K6821 Chamber" mecha from the series. This mecha based on Chamber's design is known as the "Machine Caliber Avalon Guard," and features an original color scheme devised by the mechanical designer for the series - Makoto Ishiwata. The Avalon Guard is a mecha created to defend the Galactic Alliance's 'Avalon' space colony. This color scheme never featured in the anime itself, but can now be added to your collection!
This item is expected to be released on or about 05/31. We will accept additional orders at that time if supplies are sufficient.