PrO2 Oxygen is a conveniently-sized container of cooled, high-purity, breathable oxygen to aid in the recovery from a variety of physiologically stressed or impaired conditions Revitalizes during periods of physical or mental lethargy and stimulates the body at times when peak performance is required. The canister comes a blue inhaler cup-adaptor for the user to place around the mouth, press down and inhale.What makes PRO2 special is that it contains an adsorbent which is specially designed to store a much larger volume of oxygen than could be otherwise stored using compression alone. For this reason the device contains and delivers up to three times the quantity of similar container volume products, offering by far and away the best value breathing oxygen on the market.PRO2 contains a granular adsorbent and is the reason why the canister will still feel partially full after the gas has been discharged. PR02 contains 22 litres of oxygen in a 650 ml canister. Dimensions: Diameter 65mm, Height 210mm.