The less expensive of the two will cost you $70 and it works by utilizing a 3.5mm port. So it has a direct wired connection, but not all stereos have that port to plug into. Making the slightly more expensive option a great find for those with not so great stereos. The more expensive one is still only $10 extra at $80 a piece. It works by auto scanning for a free FM channel and then settles on the one that has the absolute least interference. The TuneBase Direct which is the cheaper of the two will start shipping out early this month and the TuneBase FM will ship mid-July.