Yonex precision MAVIS Nylon shuttlecocks are the closest you can get to traditional feather. Designed to have the same flight time as a feather shuttle they give an accurate and durable performance with a traditional feel. Players should always use the shuttlecocks best suited to the playing environment. The hardness of the skirt the feather part of the nylon shuttlecock varies depending on temperature. In the cold as the skirt becomes hard it is prone to breaking. In the hot the skirt becomes softer and less likely to break but the feel at impact is affected by the softer skirt. YONEX manages product quality by categorising MAVIs into 3 temperatures. Please ensure that you choose the shuttlecock best suited to the playing environment. Color of the cap - Proper speed- Range of temperature: Green slow 22-33 C Blue middle 12-23 C Red fast 0-13 C Shuttlecocks should be stored away from high temperatures and the tube kept upright with the cork side of the shuttlecock facing down