Pepper sprays, Mace sprays, tear gas, self defence sprays, OC sprays, these are all terms to describe the liquid containing the active ingredient Oleoresin Capsicum (OC). OC is a chemical compound that causes irritation to the nose and eyes causing pain and temporary blindness.
OC is derived from from the fruits of the Genus Capsicum, or chilli plants for those of us that don't speak science.
Spraying a person with a pepper spray is legal when used for self defence in most countries. The attacker when sprayed will feel immense pain, the inflamation of the eyelids will cause blindness allowing the victim to make an escape.
Security-Store sells a number of different pepper sprays. Their main dfferences are whether they deliver the OC spray in a fog like an aerosol spray, or in a direct stream like a water pistol.
Fog sprays are effective outdoors and aim is not too important. These also work well on animals.
Direct stream sprays are better indoors or in a vehicle, but you do need to be more accurate with your aim.