When evaluating pepper spray, it is quite important to understand what you are buying because you are going to utilize a self defense device that may save you and a loved ones life.
The strength of pepper spray is determined by OC (Oleoresin Capsicum) and the SHU (Scoville Heat Units). The OC is a base resin and depending on the manufacturer they will say they have 2% OC such as Fox Labs and others will say 10% OC, what is important is the purity of the OC Resin they are starting with not the percentage. Put this in perspective a jalapeño pepper has a SHU of 5000; a habanera pepper has a SHU of 15,000. Now most Pepper Spray manufacturers have a SHU of 2,000,000 to 5,300,000 which is considerably stronger than any pepper you may eat, and habaneras are HOT!
Many Pepper Spray Companies use a higher percentage OC but also uses a less pure form of OC Resin, thus making it very misleading who’s the strongest and best. Although Fox Labs is a 2% formula it is a very pure form of OC resin and has a quicker reacting time, and seconds can count when defending your self or your family. That is why a 10% OC resin may sound better but since it is less pure the reacting time is a bit slower.
Nozzle heat is a catch phrase or buzz word a lot of the manufacturers use. For example, a 10% OC on a 2,000,000 SHU is a 200,000 nozzle heat a 2% OC on a 5,300,000 is a 106,000 nozzle heat. Now the logical view would be the 10% is better, not true because the 10% OC is a less pure form of OC resin thus not affecting the attacker in the quickest and most productive way.
Bottom line is doing your homework on what you are buying, go to the manufactures websites and see the SHU concentration. The higher the number the more pure it is thus the percentage is secondary.