I wish I could link what they look like, but I don't recall the name and I don't have a guitar rag with me at the moment.
They look to be rubber bands that connect all four fingers together to minimize excessive movement on the fretting hand.
The reason I ask is because the number one problem I have in terms of speed, accuracy, and efficiency is that my fingers just "fly up" too far naturally. This is something that's been a habit for a really, really long time, going back to my guitar lesson days when I was 16 or so.
When I concentrate heavily (literally staring at my hand) I can minimize it, and sure enough things become cleaner and faster.
The appeal of these bands is that it would hopefully train the hands to do so, hence my curiosity as to if anyone's tried them. I'll post the link if I can find it later.
I have the exact same problem. It blows.