Features:A unique double chamber design that produces 2 different high waves.Made of ABS material, high strength, very durable for use.Portable size, easy to carry and use.Suitable for personal or professional use.Can be applied for basketball, football, volleyball etc.Descriptions:3.74KHZ and 4.10KHZ mix wavelengths, making the sound quality of steel and penetration.Specifications:Material: ABS+ titanium alloy + polymer material + ropePackage included:1 x Authentic Referee Whistle 1 x Lanyard (Random rope)1 x Storage Box (Box color random)Notes: Due to the difference between different monitors, the picture may not reflect the actual color of the item. We guarantee the style is the same as shown in