The Ongaro blades I used are 14" P/N 33014 The blades came with adapters for different types of arm ends.
I used 1 each of the following arms, both are 'J' hook :
The 33650 is a J hook but the end is straight so the blade is inline with the arm.
I now know I should have simply bought two of the 650 as the angle adjustment was not really of use for me. Also that feature added a problematic extra bit of length to the arm. I won't change it but mention it so you are aware. Your windows may be slightly larger and maybe the angle adjustment would be of use.
The 660 I have had now for two years.
The 650 was installed last summer, so one year.
My intention is to do the centre window this year. It has lasted because it gets the least use and I still have a spare arm and blade. Regardless I will change it this year.
Hope this helps