Many Series I SoundDock serial numbers start with '0357' or '0402'. If it does not mention the words 'Series' or 'Portable' then it is a Series I. If you check the sticker on the bottom, above the serial number, it should say the name of your SoundDock system. SoundDock III speaker Located on the bottom of the speaker SoundDock XT speaker Located on the bottom of the speaker Stereo Speakers Companion 5 computer speakers. Serial numbers are 17-digits long following “S/N” and contain letters and numbers. Support for all computer, docking, bookshelf, outdoor, and floor standing speakers including: Companion and MusicMonitor computer speakers, powered and non-powered floor standing speakers, 201/301 bookshelf speakers, 901 speakers and all made for iPod SoundDock models.
