I contacted Rosen about this and their reply is below</pre><tt>The FM modulator located behind your vehicle's radio will have a switch to
adjust frequencies. If it does not your local stereo shop can install another
modulator that will broadcast on a freqency you desire.
Thank you for contacting Rosen Product Support</tt></pre>I have checked behind my stereo and I can not see one fitted in my car.</pre>They are available here for about £20 http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=270466870467&ssPageName=STRK:MEWAX:IT#ht_2149wt_1165</pre>Mark</pre>