1Whistle original mouthguard, prolong the service life. ABS resin strengthened whistle mouth, stable and chewy. 2Applicable to various scenarios, basketball, football, volleyball games, traffic guidance, military training and so on. 3High frequency boom, lightweight and portable. Considering that human ears are more sensitive to the audio of 10004000Hz, the treble frequency is set to 4000Hz. 4Adjustable nylon hanger, hanger easily through the tail hole, double ball fixed hanger length, not afraid of losing, not afraid of falling. 5Two independent sound holes. In a volleyball match, the referee is located in the middle of the court. The professional volleyball referee whistle, and the sound can be transmitted to both sides.
