Moth with a strange tail

Moth with a strange tail

Observation - Moth with a strange tail - Hong Kong. Description: I saw this moth (length probably around 20mm) in a building on a mountain in Wan Chai, Hong Kong. It's probably easy to identify, but I have only a very superficial grasp of Lepidopteres, so maybe someone can help me out? :)

I saw this moth (length probably around 20mm) in a building on a mountain in Wan Chai, Hong Kong. It's probably easy to identify, but I have only a very superficial grasp of Lepidopteres, so maybe someone can help me out? :)