Natural shuttlecocks from Yonex come from Chinese geese. The springs are by-products of the food industry. The five different products differ only in their quality. This is expressed by the number. The higher the number, the smoother the ball flies and the longer it lasts.
The AS-40 is for the 3-5. League of Interclub Championships approved. Otherwise, it is known as a first-class training ball, even for unlicensed players.