TrolMaster’s Hawkeye provides an economical and accurate method of monitoring an enclosed space. Some users simply need to monitor temperature, humidity, CO2 and VPD levels without actually needing to control any devices. The CM-1/Hawkeye is specifically designed to be used as a back-up monitoring system to ensure environmental conditions are maintained within acceptable limits. The Hawkeye comes COMPLETE with everything needed to measure temperature, humidity, CO2 and also provides accurate VPD measurement. (Vapor Pressure Deficit).