its an FM Modulator,
any modulator that broadcasts over 0.5w (IIRC) is illegal as you need to buy a licence (in the UK) anually to use this item.
the ones that are legal are crap, the sound quality is poor.
you can get then for your phone, Car Baby was the first in this country.
There are two types of FM Modulator
Over air and in-line
Over Air
how an FM Moduator works is its basically a tiny FM transmitter, like the BBC use for radio 1 etc, it transmits a FM signal on a suposidly un-used frequency. you then tune your radio in to it. i personally dont like them, ive used then before and the quality was sub-standard at best. plus the fact that other people can tune into your signal, thus halfing the quality going to your unit, it use up alot of battery power (unless you pay £20+ for a car charger.) the other rhnig is volume, a FM Modulator will not/can not normalise the volume and bass/Mid/Trebble settings for you. you will have to make sure everything is flat on the iPod when you get in the car and then use the settings on the head unit. it can be tricky to get the right balance to stop distortion but it can be done, but IMO its still bad quality
In-line is a little bit better sound quality, it pulg direct inline of the aerial ti the back of the Headunit, and sometimes can also power the Ipod, Halfruads do a revo for £30 that can do this but i still odnt like them as the Headunit can not control the item. you still tune your Headunit to a frequency but no one else can tune in to it, this is one way to get round the 0.5w legality as it needs less of a signal to push the sound down the cable
i prefer hard wired in, cos then most Headunit will also control the IPod as well, and it will normalise the volume Bass, Mid and Trebble setting on the iPod.
if you have the iPod in your car and it is not attached to the dash securely and you are driving whilst changing tracks you are breaking the law, and if a copper see's you it the same penalities for holding a mobile phone
its Airplay (well one make) for the Ipod
