1. The document describes the components of the HOT system which monitors firefighters' core body temperatures, including wireless RF tags, temperature sensors, and a PDA with proprietary software. 2. The temperature sensors are designed to measure forehead skin temperature as a proxy for core temperature in a non-invasive way, and transmit data to the PDA via RF tags. 3. The PDA software allows incident commanders to monitor temperatures in real-time, access individual firefighter's medical histories and emergency contacts, and view help guides for responding to overheating.