72 hours unlimited rides in Hongkong

Well, it is applicable to all MTR lines (except additional ride on AE train, East Rail Line first class, travel to/from Lok Ma Chau Station and Lo Wu Station), Light Rail and MTR Bus (Northwest New Territories).

The 72h unlimited ride starts from the recorded entry time of the first MTR train journey, and lasts 72 hours plus any additional hours up to the end of train service on the last day. So, you can use it from 8am on Day 1 up to late night of Day 4. :)