I'm a bit uncertain if I like this patent or not. It sure works GREAT for small diameter stuff, but moving up to say 4" the triangular handle will hit the log when you're halfway through. This limits the length of the cut: You cannot use long strokes anymore, just short strokes with the middle part of the blade.
I used it to clear some land a few weeks ago including stuff over 10" in diameter. I just had to change the angle of attack occasionally. It went through willows and Chinese tallow trees like butter.
-Blast