I've tried generic Made in China versions of this (which I'm sure is where this guy is getting them and repackaging them) with varying success. The trick is you have to get the right size for your finger(s). When you buy random ones from China on eBay or Amazon, sometimes you won't know what size you're getting. And if it's too big, then you won't get good tension to push the blood through your fingers. But if you get the right size, you might get good results.
Another option is the finger roller, which I thought was a bit better because you don't have to worry about getting the wrong size and it does the same thing.