Kind of a strange device, from Korea. They essentially are wheels you can tie to your shoes. Sounds like inline-skates so far. BUT there are only 2 wheels per foot, and they are both at the heels. So, it needs some practice, but after that, you'll sure get lots of attention ;)
A: "Whoa, look at him, he's floating"
B (yawns) : "No, he's got PLIWS. Man, you sure are stupid..."