Featuring a coreless design for a louder, more penetrating, crisp, and loud whistle. The Dolphin Whistle sound can start to sound from 3.5 milliseconds, the sound is one step faster, better to maintain the order of the game. Made of ABS hard plastic, hygienic packaging, safe material, more assured use. Waterproof and rustproof, can be used even on rainy days, and can be washed directly, without fading. Equipped with lanyard, storage box, and tooth guard. Measuring 2.5*0.8 inches, this custom training competition fish mouth whistles. Usage Scenarios: Office supplies, school stationery, corporate promotions, trade show giveaways. We offer logo printing and full packaging customization. Product Highlights: Portable, durable, practical for daily use.