Features: Make of plastic materials, light weight, Enduring, and can withstand long terms use. Having clear and loud tone makes it easy for referees to convey instructions in noise environment. Comes with lanyard. You can simply wear it around your neck or hangs it on wall to free your hands. Suitable for various sports competitions and referee occasion, such as basketball, football, volleyball. The designs is simple and easy to operate, and referees can easily send signals and instructions through whistling. Specifications: Materials: Plastic Styles: Small Whistle/Large Whistle Small whistle size: about 4x1.6cm/1.57x0.63inch Big whistle size: about 4.5x1.70cm/1.77x0.67inch Package Includes: 24pcs Small Whistle/20pcs Large Whistle note: Please allow 1-2cm errors due to manual measurement, make surely that you not mind before order. Due to difference between different monitors, the picture may not reflect the actual color.