Pepper spray is an aerosol spray made with the refined product of a hot pepper slurry, the active ingredient being oleoresin capsicum and the major capsacinoids. The spray will also contain other agents to ensure the spray is uniform in content and a propellant. It is used to cause temporary blindness, pain, shortness of breath, mucosal membrane inflammation and swelling and incapacitate an attacker. You should only use pepper spray if you are threatened or your life is in danger. It is illegal to use pepper spray in an offensive manner against another human being. A good spray will disorient and de-focus an attacker allowing you to escape or take control of the situation by obtaining assistance. A food product company makes the hot pepper base formula from hot peppers and sells it in different grades of refinement or heat value. The heat content of the formula has been a subject of much debate for years. Your choice is not that difficult because all the pepper spray on my website is stronger than most of what many police departments still use. Nevertheless, several advertised components of the formula should be explained. OC Percentage: How much of the base formula comprises the net weight of the contents. A 10% formula is one where 10% of the ingredients in the can are the pepper formula. Heat Rating: Usually listed in terms of Scoville Heat Units. This figure describes the relative heat of the pepper component(base formula) on a scale. Pure OC (oleoresin capsicum) is 15 million SHU (scoville heat units). Fox Labs uses a base which is refined to 5.3MM SHU. Police Magnum brand uses a 2.0MM SHU formula. You probably do not relaize this but the most widely used pepper spray by the greates number of police departments is only 500,000 SHU and at a 5% concentration and has been for years. Why is a moot point. Suffice to say it involves corruption and hard business. Most human beings cannot discern with much certainty the difference between hot and hotter and hottest. Once you get it in your eyes you don't care. So the differences are mostly academic and all my pepper sprays are extremely effective and work very fast. I have police departments that use all of my pepper sprays, so there are professional recommendations on all of them. Pepper spray is also very effective in providing defense against animals, too. Besides our bear spray, any of our sprays will repel all kinds of critters including dogs. The US Postal Service has been using pepper spray since the 1950's and still does.