Quality materialThe whistle is made of high quality aluminum alloy,surface anti-oxidation treatment, no fading, no rust and durable waterproof, rust-proof, can be used for a long time Easy to use and carry:This aluminum whistle is small and portable, 4 7 cm/ 1 85 inches in length, diameter of the these whistles is approx 0 9 cm/ 0 35 inches with a key ring ,compact and strong, elegant personality, can be hung on the key ring as an ornament, portable design, easy to carry around Loud whistles:The notch design of the whistle increases the vibration frequency of the air, the high frequency is louder , and the transmission distance is long, very useful for various emergency situations; During outdoor travel, you can confirm the direction for you, avoid getting lost, find companions, etc Multi- purpose : Emergency tools aluminum safety whistle for a variety of occasions,not only suitable for emergency situation in sporting events,such us camping,hiking, boating,hunting,but also used as referee coaches whistle for tournament,or pet training