Buy pepper spray that has at least 10 or 15% pepper and at least 2 million scoville heat units. Most units cost between $10.00 and $30.00 dollars, a small price to pay for peace of mind knowing the unit is new and ready to protect you once again. Never buy cheap pepper spray or cheap tear gas it will only get you in trouble. There is nothing worse than an angry attacker.

You should test your defense spray at least once a month. While outside, point away your OC pepper and spray it for a brief squirt . Note how far the spray goes and see if it's as full as it was when new. If the range is less than 3 to 4 feet or the spray seems to be thin or weak, go and buy a new pepper spray immediately. Do not rely on it! Most sprays, even ones that have an indefinite chemical shelf-life, can lose their pressure over time, much the same as a fire extinguisher.

If you use your defense spray against an assailant replace the unit immediately. Don't rely on it! In the excitement of the assault you may not realize just how much was sprayed. If you have to use it again there may not be a sufficient amount of pepper and spray to do the job.

For a finial note. I can not stress enough that cheap pepper spray or cheap tear gas can get you in trouble. Buy pepper spray that is high quality and brand name. I would personally not trust my life to a generic brand of defense spray.