A variety of applicable environments, outdoor travel, military training, distress, danger warning, and so on. Made of durable aluminum alloy, strong and durable, beautiful and fashionable. Integral molding, no ball design, water, and dust can be blown. Single tube popping design, high-frequency penetration, up to 120dB, wide range coverage. Can be hung on the backpack or hung on the keychain, do outdoor survival, and training use. Made from aluminium alloy material, measuring 1.85*0.35 inches, this custom portable aluminium alloy whistle. Usage Scenarios: Office supplies, school stationery, corporate promotions, trade show giveaways. Customization: Logo printing available with multiple packaging and color options. Product Highlights: Portable, durable, practical for daily use.