I decided to pay a little more for this lighter-weight aluminum carrier.  I wanted a unit that I could easily install on my SUV by myself.  This unit fits the bill quite nicely.  It's 28 pounds light and very well made.  It is also easy to assemble.  The primary strength members are steel but the frame and mesh floor are aluminum.  It has the same 500 lb. carrying capacity as the all-steel units.