Hohner Auto Valve

[GP Grant <s0234576@xxxxxxxxxxxx>]

I recently came across the Hohner Auto Valve Octave Diatonic Harp in my store 
by store search for XB-40's in Toronto last week.  I had never heard of it 
before.  

Besides the fact that it's an octave harp, is there any difference between the 
Auto Valve and the XB-40?  If so, is there a non-octive-harp version of the 
Auto Valve - i.e. another fully valved diatonic?  If not, why did it take so 
long to come up with the XB-40?

Thanks

G.