3X Walkera QR Ladybird Propeller Props Blade Set 12Pcs for Hubsan X4 DIY Quadcopter 720 820 Motors
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Bought as spares for my U816 quad when nothing else was available. They fit perfectly and it flies better than on the original props as the improved shape of these props gives it more lift. See my comparison with the originals here: http://www.rcgroups.com/forums/showthread.php?t=1701910
I beat the crap out of these blades, straighten the corners with my teeth, bend the large creases out, disregard the chips and cracks, and keep on flying. Sometimes, I think there is no way my LB will even get off the ground after striking asphalt, stucco, tile floors, wrought-iron fences, etc. But something about the design of these blades makes them very forgiving and offers great thrust. If a blade isn't creased 3 different ways from Sunday and missing 30% of it's mass, it's not yet due for a change. :)