System-S Micro Backup Battery Charger Extender For SanDisk Sansa Clip+ Clip Plus Clip 2GB 4GB 8GB Insert four conventional 1,5V AAA-Micro size batteries into the pack and have a portable power source Total running time with connected battery adapter will be extended for hours (depending on the used batteries up to 8 hours) Eliminates traveling with a ac adapter or charging cradle Charges your battery or provide backup power Lightweight , slim and compact size