These four high performance propellers have been specially designed for the AR.Drone by a team who won the French Army Micro Drone Contest. They are moulded from tough flexible plastic to optimize power、 consumption and thrust. The two pairs of propellers are marked either ?C? for clockwise or ?A? for anticlockwise、 as they rotate in opposite directions. The propellers should be mounted as follows  Motor 1 ?C? - Motor 2 ?A? - Motor 3 ?C? - Motor 4 ?A?. This kit includes 4 x propellers  2 x ?C? and 2 x ?A? plus 8 x circlips. For easy assembly、 a special circlip tool is available in the mounting tools kit、 to insert and remove the circlips that hold the propellers and gears on the shafts.