Compatibility summary
You will need a travel adapter in Hong Kong; plug types used there differ from United States. Voltage differs by more than 20% — a voltage converter may be needed for some appliances.
Plug comparison
United States plug types: A B
Hong Kong plug types: G
There is no common plug type between United States (A B) and Hong Kong (G). You need a travel adapter.
Voltage comparison
United States: 120V, 60Hz
Hong Kong: 220V, 50Hz
Voltage converter recommended (United States 120V vs Hong Kong 220V).