Others have mentioned the Nichols Ultra-wings. I have used them and appreciate the fact that they maintain original working width as they wear. I didn't appreciate the fact that they got a bit cutesy with the 'swoosh' along the leading edge. They would have been a lot better sweep and less prone to shoving and ridging if they would have left the front edge straight.

If you're concerned about that aspect, you might take a look at the McKay clipped wing sweeps. I use them on both my Concord air seeder (11" knock ons) and my Flexi-Coil 820 (16" bolt ons).