We didn't think they needed to be checked periodically either.....until we decided to unwrap them, orally inflate them, and then check the cartridges. 3of the 6 we carried had seams that had "unglued" themselves( was less than 18 mo old), 1 indicator was bad, and 2 of the cartridges had significant corrosion on them-may have worked but who knows?? Now we check them ea year, orally inflate and leave for 24 hrs, and if they go soft they are replaced. When you need it to work, I want to know it will work....cheap insurance!