Method of use - Put it on a scuba tank, pull the strap into the water, and when you let go, the ball will hit the tank with a loud sound, which will make it easier for you to be heard by your partner or others.< /p>Much louder - Put it on your scuba tank, shoot the ball, the scuba tank knocker sounds much louder than others diving equipment, practical diving accessories.High elasticity - The strap part has high elasticity, which the diving knocker ball can be used on most cylinders of different sizes, can meet your different needs.Lightweight Material - The scuba tank knocker is made of silicone and PA66 material, which is lightweight, easy to carry, durable, can be used for a long time.Easy to use - The knocker ball is easy to hold and use in any situation. ion and an underwater environment, increases the possibility of being helped under special conditions.< /p>