Duracell Powermat for 2 Devices (PMA compatible)-Black Sleek charging hub provides wireless power for any two Duracell Powermat-enabled smartphones or Portable Backup Batteries Use Wireless Case* to drop and charge your iPhone 4/4S.Never overcharge your phone when is fully charged Wireless Case or Portable backup Battery required to enable phone Phone sold separately Duracell PowerMats are PMA compatible (not compatible with Qi) DOESN'T work with protective phone case on.DOESN'T work with Powermat charging rings To start, simply plug in the Powermat and attach your Wireless Case (sold separately) to your smartphone