1.[Quality materials]11' Double Ball Aluminum Alloy Extension Arm is made of aircraft-grade aluminum alloy with hard oxidation treatment to resist deep-sea corrosion. The skeletonized design makes it lighter in weight and less resistance when used underwater, making the camera equipment easier to operate and control, making it the ideal dive gear for underwater diving photography 2.[Compatibility]Length: 11''/27.94cm; Sphere size: 1'/25mm; Weight: 3.21oz/91g. Compatible for all arm systems that has a ball head which diameter is 25mm/1 inch.Multiple dive rigs (e.g. fill light, buoyancy arm, etc.) can be attached by extending the dive light arm 3.[Stabilise]The 1'' ball head is equipped with a rubberized O-ring that prevents friction when the unit is attached and provides a stable, secure support for the lighting system, preventing the unit from moving or shaking during filming, making it ideal for use during diving, snorkeling, and other underwater activities that require illumination in order to capture clear, vivid images 4.[Expand as you wish]The double ball extension arm with butterfly clips can be multi-directionally attached to fix the flash or video light, and you can rotate 360-degree to adjust the angle of the light to get the lighting effect, so as to take the ideal photos you have in mind