Question about Edelbrock 7577 magnum airgap manifold

When looking at these manifolds online, Summit, Jegs, etc.
Some pics show the manifold has two extrusions sticking up off the front runners, with threaded holes in them. Other pics show a manifold without these same risers, or extrusions.
For example look at it on Summitracing, they show two pics, one has it, the other doesn't.

So what are these for? and How do I know if i'm going to get one with or with out?

you can see them on the attached pic.

007577_v1_20110916.jpg