This Set of two high density foam buoyancy tubes is the medium sized set offered by Hyperion.
The measurements are as follows: outer diameter: 5.5cm, inner diameter: 2.5cm, length: 7cm. The buoyancy capacity of the medium float tubes measures +0.14kg each.
The medium float tube set comes with two cable ties and stopper rings so you can attach the tubes safely to your preferred camera system.