Acording to wikipedia, Mace is the genericised trademark of Chemical Mace, the brand name of an early type of aerosol self defense spray inventedby Allan Lee Litman in 1965. The first commercial product of it's type was CN tear gas desolved in hydrocarbon solvents packaged into a small aerosol spray can, useable in almost any environment and strong enough (when sprayed in the face) to act as a credible deturrent and incompacitant. It's popularity led to it's brand name being shortend to simply "Mace" for all defense sprays (regardless of the composition). The original Chemical Mace formula using only CN has since been discontinued. Due to the potential toxic nature of CN and the generally superior incapasating qualities of oleoresin capsicum (OC) pepper spray in most situations, the early CN has mostly been supplanted by OC formulas in police use, although Mace Security International still retains a popular "Triple Action" formula combining CN,OC and an ultriviolet marker dye. Mace is also a company name that sells different pepper sprays which are legal to carry in the US. For more information on pepper spray read my post on pepper spray or go to wikipedia. I hope this post helps you.