【airflow design 】--This whistle adopts great airflow design, it can easy to whistle and make a loud, clear sound. 【compact size】--Compact size and portable mode,only weights 13g you can hang it on your bag or the key ring, very convenient to carry. 【application】-- The loud whistle can be heard for far distance, suitable for diving, camping, hiking, etc. 【indispensable accessory】-- Emergency Whistle is an indispensable accessory for outdoor sports lovers and a unique gift to you friends. 【three colors】--Nylon Emergency Whistle has 3 colors，Gray, Yellow and Green，orange， available in 3 different colors, you can choose according to your needs.