Support 18W fast charge, the use of 20w charging head (and 18w charging head charging speed is about the same) is OK, the phone and charger will automatically identify, adaptive charging process is still relatively safe, you can rest assured to use; There will be no effect on the phone, you can rest assured that the use of charging.
18w 20w charging These two are generally 9v2a and 5v4.5a, that is, 18w and 22w fast charging. It's a quarter faster than the former.