Sherwood 6 cu ft 3000 PSI Aluminium High Pressure Spare Emergency Tank Cylinder with Valve for Scuba Diving Pony Bottle A must have for your dive Comes with a yoke design valve, 6 cu ft., about 0.9 liters, Pressure: 3000 PSI, Length without the valve: 10.80", Diameter: 3.21", Weight with valve: 3.9lbs, Buoyancy full: -1.5lbs Buoyancy 500 PSI: -1.1lbs, Sherwood Valve model #5000K-48, High visibility yellow makes it easy to locate