I've seen a couple different ones, I've seen an ultralight one that has a flange machined into the back edge so you don't need the big guide washer.
then of course there's the findenza adjustable. I have seen them on some sights as being different degrees for different colors. 3 degrees for silver, 6 for blue, etc. I thought they were all the same range, but perhaps not.
What do you guys use and recommend?