This whistles is made of plastic material which are strong and durable. It is designed to give you the best chance for survival in a disaster or lift-threatening situation. It also can be used as compass or thermometer when you lost direction and need rescuing in wild. Features - - Material: Plastic. - Size: 6.5 x 3 x 3cm. - High-decibel survival whistle has functions such as gathering, confirming orientation, and calling for help; - The direction of the compass is more stable than original one, and the horizontal bubbles in help to determine the horizontal position; - The thermometer can help you monitor the ambient temperature to prevent sudden changes in temperature. - Suitable for camping, hiking, mountain climbing, cross country and other outdoor activities. - A convenient and practical tool for your friends and family. - Warm Tip: Dear buyer, Due to lighting effect, monitor's brightness, manual measurement and etc., there could be some slight differences in the color and size between the photo and the actual item. Sincerely hope that you can understand! Thank you! Package list: 4 x Whistles