You no longer have to compromise performance in your portable audio experience.This mini speakers are a pocket sized power house with a patented retractable cable system so you don't have to worry about carrying extra pieces or cords getting tangled during transport. These portable mini speakers magnetically fasten together and are only 2-Inchx4-Inch when connected, making it the perfect size for quality sound on the go. Each speaker twists open to expand for extra resonant bass. The lithium batteries are fully rechargeable through the included USB Y-cable or your MP3 player's AC adapter. (AC adapter not included). Perfect for MP3 players, smartphones, portable CD players, netbooks, laptops, and desktop computers, the Mini Power speakers come equipped with a standard 3.5mm headphone port for easy plug and play.