rear hatch wiper size?

[schmedes1]

I did the "search is your friend" angle, but did not get a direct answer to the following question:

For the 85.1+ 944 hatch wiper, what is the largest wiper blade you can install and still do the best job?

[FRporsche]

I don't remember the actual size but you can definitely get a blade a few inches longer than stock. I think it was 19"??? It fits and works better than the stock.

But I don't run a rear wiper anymore - those things are ugly!