Like Balunian dogs, and possibly other species from their homeworld, Balunian humanoids have a unique physiology. Their bodies are similar in structure and design to balloons. Because of this, they are often referred to as "Balloon people."
Their balloon-like bodies allows them to inflate or deflate, thereby increasing or decreasing their size at will. They posses air valves in their hands, one for each. They also have a larger valve on their chests, which when opened allows them to deflate much quicker.