One cnc-machined and anodized aluminum arm used on the QAV540. These arms also fit on the QAV500. On the QAV500 they enable up to 12" props to gain efficiency and flight time. 11" or 12" props on these arms produce vibrations that are more difficult to eliminate in the camera video image. These arms can also be used on a QAV500 with the brushless gimbal upgrade.