Innovage wireless headphones use a transmitter that transmits your audio over FM waves. I had a very hard time getting my ipod to play on it, the FM radio would always override it. If I sat in a certain place, I could get it to work ok, sound quality lacks, but I bought these to be mobile, and I can't use them for that. Overall a very big disappointment. The batteries go in the back of the headphones, making them a bit bulky. They don't fit me very well. The instruction manual was very vague. The controls are somewhat confusing and the transmitter is a little bulkier than I expected. If you needed a set of simple FM radio headphones, these are an ok buy, but I cannot pick up any stations at my work, inside the building. They require 4 AAA batteries. When I could get it to work with my ipod, it didn't even sound like it was stereo. Overall I am very displeased with this product.