SD-card counterfeiting is truly rampant online (e.g. eBay). A 2GB card is modified to look like a 16GB card (both the packaging and the actual interface circuit, so it even tricks your computer). The card works fine until you use more than 2GB; then data corruption occurs.
This 16GB card is a good 40% cheaper than anywhere else I've seen, so I was initially very suspicious. Amazon is certainly reputable; however, in this case the seller is some third party (BoBoTECHNIC), and Amazon is shipping it on their behalf.
"H2testw" is a standard program used to verify SD card legitimacy. It writes a bunch of data to the card and then makes sure that it reads back exactly what it wrote. I am happy to report that the card passes the test.
Incidentally, the card holds 14.8GB (differs from 16GB due to marketing tricks that SD card makers play). H2testw averaged about 3.4MByte/s on both reads and writes. It takes about an hour to transfer 15GB to the card.