Granted, this is just a listing on a bargain site, but seems like this is either the wrong cassette or it's missing a ring!
Chainlove at it's best.
Still, this is a really cool cassette. The top 8 gears are made from one piece. Here is a look at how the manufacturing process works:
Steps 1 - 4
You can see that they start from a block of aluminum. This makes them (apparently) lighter and stronger than a conventional cassette. Conventional construction is to have 7 or 8 individual cogs all pinned together with steel pins. Here's another helpful cut away:
The backplate is the top gear and I believe what is missing from the picture in the Chainlove image above. And at $150, even if it's missing a whole gear - what a steal!