Wow -- an accessory combined, coupled rangefinder that works with multiple focal lengths! I admit that I'm a total geek when it comes to obscure/strange/interesting rangefinder mechanisms, but this absolutely makes my day! I love it when I encounter a rangefinder system I had never seen before.
Until now I thought the "Rolleimeter" attachment for Rollei TLRs was the ultimate in sheer loopy add-on rangefinder brilliance, but I have to admit this one takes the biscuit!
I don't suppose there's any provision for altering the viewfinder to cover the various focal lengths it accepts...?
Also, how does it handle in practice? Is it fiddly to use (changing lenses, for example) or reasonably convenient?