Why It Matters: Environmental conditions significantly affect shuttlecock flight. High altitude and warm temperatures make shuttles fly faster, requiring slower speed shuttles.

Speed Numbers: Shuttles are numbered 75–79 (or 1–5 in some systems). Higher numbers = faster shuttles for cold/low altitude conditions.

Testing: The BWF standard test involves hitting a shuttle from the back line. It should land 530–990mm from the opposite back line when hit with full power.