via this auction
"First of all, it’s certainly true to say that it’s much larger than the regular Stylophone – which is, after all, about the size of an inch-and-a-half thick postcard.
The 350S is a souped-up Stylophone in every way: instead of the Stylophone’s 20 notes – an octave and a half – the 350S has 44. That’s three and a half octaves, and you can see in the picture the difference in length between the two keyboards.Not only that, the 350S has eight voices, as opposed to one (or even the S1’s three), and some of these are themselves in different octaves.
The voices are designated ‘woodwind’, ‘brass’ and ‘strings’. In these days of sample-based synths, none of these sound terribly much like what they say they are, but they have the general qualities of these instruments – and, despite what you may read, one or two of them are quite like the distinctive tone of the regular Stylophone that we all know and love!"
You'll find additional details on the 305S at the listing or Andy Murkin's Music Electronics blog, where it appears to have been pulled from.
