a portable external battery pack for laptop, cellphone, MP3, MP4, digital cameras. can be used as the charger and spare batter 1. ... external battery pack for Notebook computer, mobile phone, MP3, MP4, digital cameras.2. This power can be used as the charger and ... charge the devices with USB interface such as mobile phone, digital cameras, MP3, MP4 ,PSP and PMP through different connection lines.5 ...