Bose has revealed its new SoundDock Portable iPod speaker system, a battery-powered take on the company’s popular SoundDock. The SoundDock Portable, which appeared on Gizmodo earlier today, features a retractable Dock, auxiliary input, a redesigned remote, and a rechargeable lithium-ion battery. According to reports, the system will run off the battery for three hours at full volume, or “much longer” at reduced settings. The system measures 6.75 inches tall, 12 inches wide, and just over 4 inches deep, and weighs just under 5 pounds. The Bose SoundDock Portable will be available at the end of September and is priced at $400.