This is a tea set that utilizes air pressure fluctuations. You pour hot water, wait a while, and when the tea is ready, tilting the teapot will cause the contents to smoothly flow into the mug. For details, please see https://www.makuake.com/project/airo/. I used it a few times after purchasing it on Makuake, but I haven't used it since and have been storing it. There is no tea staining, and it appears to be in a clean condition, but please understand that it is a used item before purchasing. There is no box, so I will pack each part separately for shipping.