So I have been thinking about heavy duty cleanups and backpack blowers that the professionals would like, and I know that the pros will want 200mph air speed for scouring wet leaves that are buried slightly in the soil, and one way to do that would be to use a traditional centrifugal design, and another way would be to use a fan that has blades that go in very deep through the tube, blades that are 10+ centimeters broad, and with a roughly 45 degree angle pitch. A fan that covers six inches of tubing would be able to handle much more restriction than a fan with narrow blades. There are two ways to get that 200mph air speed. A way to get to 1300CFM is to use two separate fans, each on a separate motor in separate tubes, so it would either be a double barrel backpack blower, or an ambidextrous backpack blower with a tube and throttle on the right and another tube and throttle on the left, the left one would be powered by a battery on the left, and the right one would be powered with a battery on the right, and they both can be powered simultaneously with both batteries installed. Each one would do 600CFM or more at 145mph or more, allowing for a total of 1200CFM or more, making it the backpack blower that can move the most air out of all of them.