Dyno sizes are now suffixed with "X" in the Heroku Platform API
Change effective on 03 February 2014
The size of dynos included with the dynos and formations endpoints on the API are now suffixed with an “X”. Valid values are “1X”, “2X”, and “PX”.
Old dyno size values (i.e. “1” and “2”) will continue to be respected for the time being.