Shoutbox

Nothing to do with computers really, but someone might know.

I'm trying to make a headset for a two-way radio, by adapting a pc headset and sticking wires onto a 3.5 mm stereo jack.  I've got the mic to work by connecting it to two of the points on the jack, but i'm slightly confused about the headphones - there seems to be two different wires - a red one and a copper coloured one, but they are both bare, without any insulation between them, which makes me wonder about the point of having two wires.  Does anyone know how I might connect these to the jack to make it work?

Thanks