The whistle with a keychain is made of aluminum alloy, which is sturdy and durable, not easy to break, deform or bend, and can still maintain its color and shape after long-term use. Their surface is glossy and smooth to the touch, providing you with a comfortable experience. The flat shape and double tubes make these survival whistles easy to blow. The highest sound is loud enough for others to hear from a distance, making them suitable as rescue whistles for emergency situations. 2 1/10'' L x 1/2'' W