According to the related thermos articles published on Zhihu website in August, 2022, the eco-bird is a double-layer plastic glass, which is not hot, and the quality of thermos is good.

A thermos cup is usually a water container made of ceramic or stainless steel with a vacuum layer. There is a lid on the top of it, which is tightly sealed. Vacuum insulation layer can delay the heat dissipation of water and other liquids to achieve the purpose of insulation.