Domestic brands. Guanzhuang Yan is also called Guan Yan, which means the bird's nest given to dignitaries. This kind of bird's nest has the best quality, is a domestic brand, and is the top grade bird's nest. The first nest built by the swiftlets is entirely based on the secretion of their throats. A lot of mucus. It is gradually condensed and has a pure texture with no hair attached. This kind of bird's nest is of the best quality.