Before you tap, you need to set up a digital wallet.

Check this M.T.A. site before you ride.

Where can I try this?

For now, the readers are only at 16 subway stations in Manhattan and Brooklyn, as well as on every bus on Staten Island (local and express).

Those stations include Grand Central in Manhattan, Atlantic Avenue-Barclays Center in Brooklyn and 14 stations in between.

Do I want to try this?

Maybe not yet.

Right now, the tap technology only allows people to pay full fare.

If you have a time-based pass (weekly or monthly MetroCard) or a discounted fare, the tap technology cannot yet accommodate you.

People using time-based passes and discounted rides will be able to use the tap technology in late 2020 , when the M.T.A. expands the locations of N.F.C. readers.

So, if you are an occasional subway rider, or curious about the technology and want to be a bit of a guinea pig, by all means go for it.