1. Selected materials Made of selected stainless steel, high hardness, good strength, not easy to rust, not easy to damage, durable. 2. High decibel whistle Double pipe whistle design, balanced, high frequency, easy to hear when blowing lightly, the decibel can be up to 150 decibels in the blink of an eye, and the volume is comparable to the sound of a BMW car whistle. 3. Stabilize the rivets The rivets not only play a fixed role here, but can also be decorated to make the whole thing beautiful and generous. 4. Seamless steel whistle The acoustic cavity is not afraid of dirt and water, and it can play its popping function even in harsh environments. Material: stainless steel, strong and durable. Size: 5.7*1.8*0.9cm. Louder sound, dual tubes can deliver up to 150 decibels, can be heard from a long distance. Easy to wear. It can be put in the keychain, the whistle is small in size, light in weight and easy to carry. It is hung in a backpack and a key chain, carried or knotted in everyday life. Suitable for children, the elderly or women.