Leoben Underwater Float Arm :

 

The Float Arm is fully compatible with all 1" ball arm system  in the market . With its high-precision machined aluminum alloy ball joint providing perfect balance between stable clamping and stress-free handling thanks to ozone-proof and weather-proof silicon rubber O-ring. 

 

 Specifications :

• Buoyancy: -680g 
• Weight: 283g  [air]
• Outer diameter: 80mm 
• Effective length: 8 inches

Other Styles of 80mm diameter of Underwater Float Arm 
 - See more at: http://www.leobendivegear.com/8-Aluminum-Underwater-Buoyancy-Float-arm-for-underwater-camera-housings-pd559643.html#sthash.UJuvSPVe.dpuf