The price of using MTR is very low. For example, the price of going from Tsing Yi to Causeway Bay by taxi is around HK$200. Travelling the same distance by MTR costs HK$11.80 for grown up people and HK$5.40 for young and very old people. People can buy a one way ticket or a Octopus card to enter MTR. Octopus card is a contact-less smart card.