Sorry, to leave you in the dark, there is a website with some more information, see www.slac-carving.com
This not a replacement for snowboarding, it´s an add on! For everyone, who likes to try something else. It is not leashed, but you can use a belt.
Turns are not only initiated by using your weight, which works at ease, it additionally has steering blades, so effective they would fire you out of the seat if used too hard . Skidding rather hard with this device, but works in narrow turns.
The key experience is the Formular 1 like position. That makes one experience speed in a new way. You can hit 50 mph easy and much faster, with next to no training, yet full brake controls and less risk of injury, since your centre of gravity is low. There is also next to no wind resistance.
And why not for those, who just have some knee issues ?! (Leg power is required for control, but no stress on the knees) But still go boarding .
It was developed by a major European manufacturer and there is a lot more tech stuff in there, that what is visible.