This Dual Tube Emergency Whistle is Machined From High Grade Aluminium Alloy for Exceptional Strength & Corrosion Resistance. It Produces Two Distinct Frequencies That Carry Over Long Distances, Cutting Through Wind & Ambient Noise to Signal for Help Effectively. the Lightweight, Compact Body Includes a Sturdy Hanging Ring for Attaching to Backpacks, Keychains, or Life Vests. No Moving Parts Ensure Reliable Function in Rain, Snow, or Dust. Ideal for Hiking, Camping, Climbing, Boating, & Emergency Preparedness Kits. a Simple Blow Delivers a Powerful Alert When Every Second Counts.