Choose the shuttlecock with the speed number appropriate to the temperature, as the difference in temperature affects the flying distance of the shuttlecock.
We should consider the temperature where we will be playing to match the right speed when buying shuttlecock.
International speed metric
1 / 75 - slow, for use in highland
2 / 76 - medium slow, for use in hotter area
3 / 77 - medium, most sea level area
4 / 78 - medium fast, cold area
5 / 79 - fast, cold area, below sea level