40+ Kevlar Helmet Expiration Date Images. Some helmets will state a given warranty period but i don't personally think they loose ballistic protection from age. Of course, there are a variety of factors that influence exactly how fast the typical body armor breaks down, including exposure to moisture, uv light, and overall use.
This is true whether the vest is made of kevlar, a composite, or a combination of industrial fibers.
Others will buy a new one on day 1,095 because they are told it's spoiled on that day. If the helmet has no date stamp it you will have to make a decision based on style and brand. My wife thinks milk and yogurt is inedible the day after the date stamped on the carton. Always buy a helmet that suits your needs and intended use.