The safety survival whistle can be used to signal for help or attract attention in outdoor situations. Suitable for outdoors, fishing, camping, hiking, hunting, kayaking, boating, swimming, surfing, sailing, water sports, referee, sports training, sporting events, etc.SpecificationMaterial: Aluminum AlloyDiameter: 9mm / 0.35 inchOuter Diameter: 2.4cm / 0.9 inchOverall Length: 4.6cm / 1.8 inchPacking List: 5 x Emergency WhistlesAdvantageFeature with a big and bright loud sound, the transmission distance is far, can be heard from a long distance, when outdoor traveling, you can confirm the direction, avoid getting lost, and find your partners, and more.It is made of aluminum alloy material, and fine workmanship, waterproof and rust-resistant, sturdy and durable, and not easy to break.