The cure for CharlieCard problems

Spatch breaks the news about a new MBTA system dubbed CharlieDiscs:

... In an innovative twist on the traditional pass system, each metallic CharlieDisc, roughly three-quarters of an inch in diameter, represents the fare equivalent of one subway ride. Customers will be able to purchase these discs individually or in groups from machines placed in each MBTA station and then exchange that disc for access to the train platforms. To add value, customers simply purchase more discs. ...