It suctions to the back of the tablet, then its flexible tail lets you prop the tablet in landscape or portrait mode. I use my Xoom primarily for watching Netscape videos or listening to podcasts while I grudgingly do housework, and the tail makes my tablet easy to prop up anywhere -- even on uneven surfaces (see below), which is not something cases with built-in stands are good at -- they tend to topple over.
I carry and use my Xoom all over the house, all day long. (We're a family of five. The housework is never-ending.) The Tablet Tail makes that all-day-long carrying-and-propping so much easier. I like the Tail. A lot.
There are caveats, of course. It needs a 3-4 inch diameter flat spot on the back of one's tablet to suck on to. This means it doesn't work with my son's iPad's current Trident Kraken protective case, as the back does not have any flat areas of sufficient diameter. But it works well on the back of tablets themselves, which is great for Xoom-users like me who rarely use cases, or iPad users with Smart Covers or any tablet user with flat-backed plastic or metal cases.
The other caveat is the price -- currently $49.99. I know there are gear heads for whom cost is a secondary consideration, and for you folks I say Go For It! I think it's also an excellent stand-case substitute for folks who only use their tablets at home, for reading, social media, and video-watching, and who either have no kids or are adept at keeping their tablets away from their kids. Or for families whose kids are unlikely to Hulk Smash! or drop their tablets. But the price is a bit of a surprise to me.
Still, I use my Tablet Tail all day long. It does exactly what it's designed to do, it does it well, it is one of those little adjustments that makes my life easier. It's a good product. If the price point is not a hurdle for you, then I recommend it.
Disclosure: Octa gifted me our Tablet Tail. However, I only write about the products I really like because honestly, who has the time?