This plug-and-play portable mini speakers design for your iPhone iPod PC Mp3 MP4 smartphones and portable CD players with 3.5mm audio jack. With a very small footprint, very ideal for travel and mobility. Give it a twist and the top portion expands, giving you extra air space which brings out the bass. You'd have to hear it to believe it. For speakers this size, it sure packs a punch. With built in lithium batteries, you can have hours and hours of listening. And with the built-in retractable audio and charge cables, there are no extra cables to bring around and no cable mess. When you need to charge your tweakers, just pull the charge cable out, and connect it to a mini USB, or use the included USB charge adapter to connect to a USB port. The speakers come in dual speaker configuration with stereo sound. With Grandmax Tweakers - Tiny Pocket Size with Room Filling Sound!