Ed,
I've recently bought and used one of these. As the photo shows, it is in two sections, front and rear, hooked together with velcro. It is made of lightweight material, but seems to keep the dust out (though not small creepie-crawlies). The fit (at least on my top) is a bit tight, but is really okay. I use it with (under) my manual hoist (the kind with four straps - Mitzi?), and it works fine. My top stays up in the garage rafters 99% of the time, and I just had a cloth thrown over it; this was a big improvement, in looks as well as in coverage.
All-in-all, I'd say it was a good investment.
-David Pease
'66 French 230SL