Not the best pic, but the only one I have as yet. Those duals are different brands. The outsides are slightly smaller in diameter and so don't touch the ground until the inners dig themselves in. The inners have chains and the outers hold them trapped in place so they don't work down between the lugs. It will push a blade full of snow or dirt until it runs out of fuel! The HY-2 lift makes using this blade a breeze.

Not sure why it came out so small. Photobucket won't let me resize it.