A fantastic little speaker that connects to any device with a 3.5mm jack connection such as iPhone, iPod, Smartphone, Tablet and MP3, the speaker has a built in lithium ion battery that can be recharged from a computer or USB mains adapter, the speaker has up to 5 hours play time with the battery.The speaker is 2 inches in diameter and only 1.5" thick, the sound is great and this is the perfect little speaker to take out on the move.