"Angled arm clamp". It will transform Sky Strider to a different racer.  Angled arm clamp available in 5 degree and 10 degree depends on how fast/large of the cource design, Sky Strider kit comes with zero degree angled arm clamp, when using  Angled arm clamp it will tilt the motor arm forward, increase the propellers efficiencies to increase flying speed . Specifications 6061 Aluminum alloy For Sky Strider 280 use only.