Sensa-15 Duck Feather Badminton Shuttlecocks. YONEX Aero. Sensa-15 officially licensed products of the last three Olympic Games as well as the major IBF tournaments. Yonex Feather Shuttlecocks are meticulously engineered for accurate trajectory under widely varying conditions of temperature and humidity. Aerosensa Feather shuttlecocks fully withstand the tremendous shocks they receive at the smash with a high-power, high-speed racket. Thanks to outstanding durability, a Yonex Feather Shuttlecock requires replacement less frequently than a conventional feather shuttlecock.Contains 12 Shuttlecocks Per Tube = 120 Shuttlecocks. Available in speeds:Slow (Speed 2)Medium (Speed 3)Fast (Speed 4)YONEX Aero