Product review (2 stars): Black peeled off after only a couple months.
These covers are attractive, arrived quickly, and do a fine job of keeping crumbs and scraps out of the burners that I'm not using, which is what I was aiming for.  (I'm not sure why a previous reviewer thought they would be useful to cover hot burners -- seems to me that covering a hot burner with a metal cover is just going to heat up the cover.)  I'd suggest, however, that anyone thinking of buying these or other burner covers be more sensible than I was and measure your burners before ordering.  The large covers are 9.75 inches in diameter and the small covers are 8 inches; sadly, the small covers proved to be too small for my stove.  I'm still very pleased with the large ones, though.

FIVE MONTHS LATER:  The black coating started peeling off a couple months in and it's just getting worse.  They look pretty awful.  I'm keeping them until I can find better ones because they still keep crumbs and scraps out of the burners I'm not using, but I'd recommend you save your money and buy something else to start with.