This set of precision-manufactured shuttlecocks ensures a perfect-fit speed, distance and stability performance. It is made of good qualitative goose feather with foam base. The shuttlecock rotates in a controllable speed of 350 to 420 revolutions to make sure a stable flight. A wonderful set for professional badminton training or amateur badminton playing. Features: Proper speed, and Aerodynamic stability and strike performance. High quality durable goose feather skirt with foam base.(for M10) The rotation speed controlled in 350 to 420 revolutions, provides smooth flight. Perfect for beginner and amateurs badminton training sports. Lightweight, high cost performance, and admirably stable. Specifications: Color: White Model: M7 / M10 (Optional) Skirt: Duck feather / Goose feather Base: Cork / Foam Speed: 76 Rotational velocity: 350-420 revolutions Weight: 4.7-5.5g (one piece) Package weight: 179g, 6.3oz / 171g, 6.0oz Package List: 12 * Badminton Shuttlecock