For headset use, the "green cable" is plugged into the headset jack of the phone. Dont know why Nike doesnt make a small as my daughter wears a size 6 and finds the sock a little large. These are sorta a niche product and I dont think people looking at these realize it. On top of this, I learned today that they turn off while charging??? What sense does this make? Any other wireless headset knows that this is a design flaw and has them ACTUALLY WORK while charging. Taking a closer look you can see the stitching is defective in the material. So he was going to take it out and replace it with another. The instructions tell you to install the skewer, so Im not sure if I got a box that was missing both of these pieces, or if they are not supposed to come with the product. Let it flow, let yourself goDoes a nice job but looks awful, comfortable tho. uhhh. soft and comfy, good looking, easy to get your feet in and out, robust rubber sole.