Koanhinn Material: metalColor: blackSize: 140*25*25mmProduct specifications about: outer diameter D20mm, length: (distance between two O-rings) 5 inchesProduct buoyancy approximately: 39gProduct net buoyancy is about: 14gPackage Contents:1 * 5-inch carbon fiber buoyancy light armOnly the above package content, other are not included.Note: Light and different displays may cause the color of the item in the a little different from the real . The measurement allowed is +/- 1-3cm.