The Flexii Finger 3D USB Optical Mouse is a replacement for your usual pointing-and-clicking apparatus. See if you can picture this: you slide your index finger into an elastic ring along the Finger Mouse's underside and use your thumb to manipulate the left and right buttons, and the scroll wheel (located awkwardly on the side of the unit). As the Finger Mouse is liable to slip, the creators offer the tip of using your middle finger to stabilize the whole thing. Just point your finger at the screen and, if you can manage it, click.
What are the advantages to using the Flexii Finger Mouse? It's marketed as being able to "help you reduce fatigue effectively," and that it's "ideal for [the] professional designer, or game fans." I do a bit of design myself, and I can't imagine using this thing. Playing games with it? Maybe a Chess app or something — anything more complex, like a shooter, and you've got yourself a handicap you don't need. And holding my hand up for hours sounds pretty tiring.
To its credit, the price is right for the Flexii Finger 3D USB Optical Mouse, for those looking to experiment: $12.