Pepper spray enables you to defend yourself while keeping a safe distance from an attacker. A one second burst to the face will cause temporary blindness, choking, coughing, and nausea-bringing the attacker to his knees. The active ingredient in our spray is Oleoresin Capsicum (O.C.), commonly referred to as red pepper. When considering which pepper spray is most effective, one must consider the percentage of pepper being used and the heat rating of that pepper (measured in Scoville Heat Units or S.H.U.). All of our pepper sprays are two million S.H.U., which is the highest available. At 17% and two million S.H.U., our Street Wise pepper spray is the hottest and most powerful. The potency of this spray enables it to bring down even the most aggressive assailants. This model has been our best seller because a person is most vulnerable to attack when getting in or out of their car. With the spray attached to your key ring you'll be able to quickly defend your self without having to waste time looking through your purse or pocket. The pepper spray cannister measures in at 3 and three-sixteenth inches x five-eights inches x five-eights inches. The included holster measures in at 5 inches x 1 and one-quarter inches x 1 inch (including the key ring).