My most usefull piece of kit in Hong Kong has been a small button compass key ring I bought in UK.
When you arrive in a new location by MTR, train, taxi, etc, when you exit the station, it is really usefull to be able to work out what direction the street is. Ofcourse if it is sunny you can use the sun, but it is not always sunny.
It is also handy to have when you are taking a long taxi journey and you are a bit nervous where the taxi driver is taking you.
