With my move to gigabit ethernet (1000 megabits per second) I was impressed by being able to move 320 gb per hour. But most of my computers have 100 megabit ethernet.
So I wondered if I could get a gigabit ethernet-to-USB converter. And of course you can. So I ordered one.
It arrived today, and I tried it. It isn't gigabit, it's 100 megabit. It's a Realtek 10/100 device; that's what lsusb tells me. And when I install it and connect it to a gigabit switch, the gigabit switch tells me that it's connected at 100 megabits.
So it's another Ebay scam, selling a 10/100 device as a 10/100/1000 device. It's only £2.99 (and I'm requesting a refund), but my guess is that the vendor gets away with this more often than not. I also reported it to Ebay, but their reporting system is very poor.