I don't own one, but the Fly-Mo has been around for quite a while. It operates like a hovercraft with a fan providing air to lift it off the ground. Most had Tecumseh 2 strokes, but some later ones might have a 4 cycle.
We had a petrol powered Flymo hover mower back in the late 1970s. Very hard work dragging it about on long grass. OK pushing in a straight line but if you need to cut curves it sure worked your arms and abs. Good for steep banks - you could lower it down on a rope.
When Qualcast brought out a range of inexpensive electric mowers they were sold with the line "It's a lot less bovver than a hover". I think I brought shares in them.