These three sizes of OC spray are with the Cop Top pressure trigger and they spray a stream. This is Foxs 5.3 million SHU level pepper spray in a 2% formula. Fox Labs International's aerosol defense spray products are formulated to be the safest, hottest and most effective you can buy! All sprays are non-flammable and are available in a wide range of sizes with varying percentages of pepper (OC). Mark 3 is a 2 oz. Mark 4 is a 3 oz. Mark 5 is a 4 oz.