The detectors are designed to alert first responders to the presence of potentially hazardous radioactive materials. The detectors were developed by several organizations, the Illinois Terrorism Task Force, the Illinois Law Enforcement Alarm System, the Mutual Aid Box Alarm System, the Illinois Emergency Management Agency, the Illinois State Police, and nuclear scientists from the Argonne National Laboratory. The detectors are about the size of a pager and can be mounted in a squad car with a holster and charger or carried by an officer on their duty belt. The detectors have various degrees of sensitivity that can be changed depending on the situation. The detectors can also be used by agencies to avoid unnecessary evacuations and road closings, thereby improving public safety.