Grandmax SPKR-GR1-RD Go-Rock Mini Portable Speaker for iPod/MP3 Players and Laptops Unique patented twist open pop-up acoustic chamber delivers enriched audio Frequency-tuned amplifier delivers crystal clear sound Built-in long-life rechargeable lithium battery. Simply recharge with the supplied USB charge cable 3.5mm audio plug connects to iPod, iPhone, laptop, and other popular devices