These are replacement props for the Blade Nano QX2 FPV quadcopter. As such, they do a good job of letting you fly the QX2. But they are NOT indestructible. Buy multiple kits if you plan to fly the QX2 a lot as you will hit walls, furniture, lamp posts, etc. Each impact bends or breaks off the tips of the propellers. Each time this happens, the efficiency of the propeller(s) decreases and with it the duration of your flights. It's amazing how little propeller damage is required to drastically…