Here's the factory description: http://www.midwestindustriesinc.com/index.cfm?fuseaction=category.display&category_id=64
These came on an upper I took in trade, and I wanted to use Magpul MOE handguards, and have done so. I like the MOE's enough that I am selling these aluminum non free float rails. They are in excellent shape. They mount solid and seem sturdy. There was a TD vertical fore grip on them when they came, you can see a few rub marks in the photos. Also visible is some carbon residue, dirt and dust, nothing major.
$100 shipped or I'll trade the rail plus cash for good quality optics––Acog, Aimpoint, Eotech, Leupold prismatic, low powered variables with illuminated reticles; dogleg AK rail from TX weapons systems; cheap surefire (small) or equivalent for carry; other stuff, run it past me.