I have just purchased and fitted these for my 27:
http://www.storka.at/index-Dateien/Page1217.htm
As I broke one of the previous ones when the cable broke and it
whizzed off the end of the wing at 2000ft, I fetted the new ones with
50kg breaking strain dyneema. I also replaced the nylon wiper with the
dyneema.

They fit the 27 great and work very well as well as looking much more
aerodynamic friendly than others I have seen. Of course in the US
without EASA you could garage them with a small mod!!

I am sure that Friedel Storka will ship to US.

Jim