I bought some for myself and my family a few years ago. It's expired now and I never replaced it. As I posted under the rad meter thread, I've had extensive rad training as a first responder and serve as a Hazardous Materials Technician as part of my job description. I can tell you that KI has its applications but will not be effective against most radiological poisoning common in weapons. If you live near a nuclear power plant it might be cheap insurance. As professionals we're taught and retaught time/distance/shielding as the best protection.