PRODUCT FEATURESThere are 12 balls in the tube.BWF (World Badminton Federation) approved.Made of 16 pieces of completely natural goose feathers.The weight of the balls will be between 4,74 grams and 5,50 grams (±0,76 grams).The flight speed of the balls is 76/77 m/s.Made of solid natural cork.A+ dur..