Synergy Digital Speaker Battery, Works with Logitech MM50 Speaker, (Li-Ion, 3.7V, 2200 mAh) Ultra High Capacity, Compatible with Logitech NTA2479 Battery - Walmart.com
Logitech mm50 Portable iPod Speakers - The Gadgeteer
Logitech mm50 Portable iPod Speakers - The Gadgeteer