I believe that people live in Hong Kong know that we can have save for HK$2 from MTR.
But I would like to tell you guys who plan to visit to HK that MTR has put some machines to save HK$2 in some shopping malls. After you have touch the machines with your octpus card, you have to travel from the designated station, then you can save your money.
The second thing, you can get one free ticket if you have travelled for 10 times with the octpus card (Only from Monday to Friday From 4 October 2004 to 18 February 2005). You can check with the information desk of the MTR stations.
For more information, please visit the below website