Digital Rights Management technology, such as Apple's FairPlay DRM used to protect tracks purchased from the iTunes Music Store, reduces battery life significantly on digital media players across the board. A recent CNET column compares various players from different companies, noting playback time while considering numerous factors such as backlight usage, track quality, and listening/viewing patterns. Music rented from Napster or Rhapsody subscription networks arrives in the WMA DRM 10 format, which "takes extra processing power to ensure that the licenses making the tracks work are still valid and match up to the device itself." CNET recently tested the Creative Zen Vision:M, which boasts a rated battery life of up to 14 hours or audio or four hours for video playback. Playing only MP3s, the Vision:M played for almost 16 hours, but upon playing back only WMA subscription tracks the player died just after 12 hours. Apple's iPod, by comparison, when playing only FairPlay AAC tracks, underperformed MP3 playback time by roughly eight percent.