PULUZ 7.9 inch 20cm Adjustable Aluminum Alloy Dual Balls Arm with 14 Thread, Ball Diameter: 25mm Features 1. Aviation aluminum material, professional diving high-strength hard oxidation treatment arm can prevent seawater corrosion. 2. Strong, lightweight, waterproof aluminum construction. 3. Use this ball arm between one ball clamps to extend an arm. 4. Unique humanization and professional water-through design, greatly enhance the use of the lamp arm under water. 5. Extend diving light arm to connect multiple diving equipment (such as fill light, buoyancy arm, etc.). 6. You can use this arm to securely attach camera accessories, monitors, lights, or underwater lighting equipment to your favorite camera system. Precautions 1. Check the light arm with a sealing ring before dive each. If there is any leakage, please install it yourself and then dive. 2. After dive each, please rinse the outer surface of the light arm with water, and store it properly after the inside and outside of the light arm.