By generating 2 kinds of sounds that are easy to hear from the human ears, it can alert people to a wider area. The spout has a cap so you can use it in a clean state. ● Can be attached to a neck strap or cell phone strap, so you can always carry it with you. Material: Body: ABS; Cap: Elastomer; Compatible Neck Strap Size/Diameter: 0.1 - 0.6 inches (3 - 6 mm); Width: 0.4 - 0.6 inches (10 - 15 mm).